Rapid synthesis of 4-alkynyl coumarins and tunable electronic properties of emission solvatochromic fluorophores

Dyes and Pigments 166 (2019) 357–366

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Rapid synthesis of 4-alkynyl coumarins and tunable electronic properties of emission solvatochromic fluorophores

T

Julian Papadopoulos, Thomas J.J. Müller∗ Institut für Organische Chemie und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1, D-40225, Düsseldorf, Germany

ARTICLE INFO

ABSTRACT

In memoriam Prof. Dr. Rudolf Gompper (1926–1999)

Novel fluorescent 4-alkynyl coumarins were rapidly and efficiently synthesized by Sonogashira coupling of readily accessible coumaryl triflates. The photophysical properties of the predominantly highly fluorescent compounds were experimentally studied by absorption and fluorescence spectroscopy and their electronic structure was rationalized by DFT and TD-DFT calculations using the PBEh1PBE functional. For certain consanguineous series structure-property relationships of the absorption and emission characteristics were established by Hammett-Taft correlations. Most interestingly, the energy levels of the underlying subchromophores can be electronically fine-tuned and addressed upon photonic excitation for placing donor substituents at the remote alkynyl terminus of the dyes.

Keywords: Absorption Alkynes Coumarin Cross-coupling DFT calculations Fluorescence

1. Introduction Coumarins [1] possess a stable embedded conjugated lactone structure and, therefore, they became increasingly important, not only due to anticancer [1d,e], anti-inflammatory [2] or antidepressant [3] activity in medicinal chemistry [1g,4], but moreover as functional πsystems [5]. For instance they are used as laser dyes [6], efficient absorbers in dye sensitized solar cells (DSSCs) [7], and emitters in organic light-emitting diodes (OLEDs) [8]. Many coumarins with simple substitution pattern can be synthesized by ringforming condensation strategies [9], More complex substituents are best introduced by cross-coupling to 3-bromo-coumarins [5] or related 4-triflate derivatives [10]. While the former were employed to establish combinatorial libraries of 151 examples of 3-alkynyl, 3-alkenyl, and 3-aryl coumarins by Sonogashira, Heck, and Suzuki reactions, the latter were recently used in Suzuki coupling to synthesize 3-aryl coumarins with cytotoxicity against colon-adenocarcinoma cancer cell lines HT29D4 [10a] and 3-(3-indolyl) coumarins with low micromolar IC50 against MCF7 breast cancer cell lines [10b]. Sonogashira coupling of 4-bromo, 4-iodo, 4-tosyloxy, and 4-triflyloxy coumarins furnishes the corresponding 4-alkynyl coumarins [11–15] but in contrast to 3-alkynyl coumarins [5] amazingly their photophysical properties remained largely unexplored to date [16]. Just very recently, as part of our program to establish transition metal catalysis initiated multicomponent syntheses of functional chromophores [17] in general and fluorophores more specifically [18], we

∗

employed 4-alkynyl coumarins as transient intermediates in consecutive three-component synthesis of coumarin-based merocyanines with aggregation-induced emission [19]. Upon observation of intense luminescence of 4-alkynyl coumarin intermediates we became intrigued in studying the photophysical behavior of 4-alkynyl coumarins. Here, we report the synthesis of various 4-alkynyl coumarins, the absorption and emission characteristics and the assignment of the electronic structure by TD-DFT calculation using the PBE functional. 2. Results and discussion 2.1. Synthesis and structure The synthesis of the 4-alkynyl coumarins 3 commences from the corresponding coumaryl triflates 1 [14,20] and terminal alkynes 2 by employing our well-established modified Sonogashira coupling [21] which uses only one stoichiometrically necessary equivalent of triethylamine. After 1 h at room temperature, workup and purification by flash chromatography on silica gel the title compounds 3 are obtained in very good to excellent yield as colorless to orange solids (Scheme 1). The structural assignment of novel 4-alkynyl coumarins 3 was unambiguously corroborated by extensive 1H and 13C NMR and IR spectroscopy, and mass spectrometry, and the molecular composition was verified by combustion analyses or HRMS. Besides the variation of the coumarin triflates 1 (R1 = H, OMe, NEt2) a broad array of alkynes 2, ranging from silyl over (cyclo)alkyl to

Corresponding author. E-mail addresses: [email protected], [email protected] (T.J.J. Müller).

https://doi.org/10.1016/j.dyepig.2019.03.038 Received 18 January 2019; Received in revised form 14 March 2019; Accepted 15 March 2019 Available online 20 March 2019 0143-7208/ © 2019 Elsevier Ltd. All rights reserved.

Dyes and Pigments 166 (2019) 357–366

J. Papadopoulos and T.J.J. Müller

Scheme 1. Synthesis of 4-alkynyl coumarins 3 by modified Sonogashira coupling of triflates 1 and terminal alkynes 2.

(hetero)aryl substituted substrates, can be successfully transformed into the title compounds at room temperature. In addition to electronically diverse p-substituted phenyl acetylenes also heterocyclic derivatives containing electron-rich reversible redox systems such as phenothiazine (see compound 3o) or the pharmaceutically relevant indole core (see compound 3p) can be obtained uneventfully.

in ethanol (Φf = 0.55) [23] or with 9,10-diphenylanthracene as a standard in cyclohexane (Φf = 1) [24]. All 4-alkynyl coumarins 3 possess characteristic intense absorption maxima λmax,abs between 287 and 433 nm with molar extinction coefficients ε in a range between 11700 and 48000 m−1cm−1. The emission maxima λmax,em can be detected between 420 and 646 nm and reveal, as indicated by the fluorescence quantum yields Φf, a strong dependence on the substitution pattern on the coumarin (R1) and at the remote alkynyl position (R2). The dyes 3f, 3n, and 3o bearing strongly electron donating substituents at R2 apparently behave differently and their absorption and emission characteristics have to be analyzed with respect to their electronic structure (vide infra). The substituent effects on the electronic properties – absorption, emission, Stokes shift and fluorescence quantum yield – were scrutinized by physical organic Hammett-Taft correlations in consanguineous

2.2. Photophysical properties All 4-alkynyl coumarins 3 give colorless to yellow solutions (Fig. 1 a), and with very few exceptions, show intense fluorescence in dichloromethane solution (Fig. 1c), some of the derivatives also possess marked daylight fluorescence (Fig. 1b). This encouraged us to take a closer look to the photophysical properties of all title compounds 3 by UV/VIS and static fluorescence spectroscopy (Table 1). The relative fluorescence quantum Phif [22] yields of the compounds 3 were determined in dichloromethane solution with coumarin 153 as a standard

Table 1 Selected photophysical properties of 4-alkynyl coumarins 3 (recorded in dichloromethane at T = 293 K). entry

compound

λmax,abs [nm] (ε [L·mol−1·cm−1])a

λmax,em [nm] (Φf)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

3a 3b 3c 3d 3e 3f 3g 3h 3i 3j 3k 3l 3m 3n 3o 3p

293 292 287 320 340 407 345 320 416 433 428 420 418 400 410 424

424 420 427 423 466 646 417 432 497 541 532 508 499 500 626 509

a

(14400) (15800) (11700) (21400) (25000) (30400) (13900) (28400) (18100) (13600) (16600) (16500) (16000) (48000) (26700) (17700)

(0.23)b (< 0.01)b (0.02)b (< 0.01)c (0.56)c (0.26)c (0.94)c (0.45)c (0.56)c (0.84)c (0.86)c (0.05)c (0.09)c (0.85)c

Stokes shift Δν̃ [cm−1]b 10600 10400 11400 7600 8000 9000 5000 8100 3900 4600 4600 4100 3900 5000 8400 4000

Recorded in dichloromethane (UVASOL®) (longest wavelength transition). Measured in dichloromethane solution with 9,10-diphenylanthracene (Φf = 1.00) as a standard in cyclohexane (λmax,exc = 350 nm). c Measured in dichloromethane solution with coumarin 153 (Φf = 0.55) as a standard in ethanol (λmax,exc = 420 nm). b

Fig. 1. Selected 4-alkynyl coumarins 3 in dichloromethane (c0(3) = 10−5 M) a) at daylight (light background), b) at daylight (dark background), and c) under a handheld UV-lamp (λexc = 365 nm). 358

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Fig. 2. Hammett-Taft correlations of the absorption maxima λmax,abs (black squares), emission maxima λmax,em (red circles), and Stokes shifts Δν̃ (blue triangles) of the consanguineous series (R1 = NEt2) of 3j (R2 = p-NCC6H4), 3k (R2 = p-MeO2CC6H4), 3l (R2 = Ph), and 3m (R2 = p-MeOC6H4) (measured in dichloromethane). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

series with a variety of σ-parameters (σp, σp+, σp-, σI, σR) [25]. The series of 7-diethylamino substituted 4-arylethynyl coumarins 3j (R2 = p-NCC6H4), 3k (R2 = p-MeO2CC6H4), 3l (R2 = Ph), and 3m (R2 = p-MeOC6H4) reveals an excellent correlation of the energies of the longest wavelength absorption maxima λmax,abs, emission maxima λmax,em and the Stokes shifts Δν̃ with σp (Fig. 2), indicating a transmission of the remote p-substituent effect through resonance and inductive pathways in the extended π-system. From the slopes of the regression lines it can be easily seen that the substituent effect is more dominant in the vibrationally relaxed excited state than in the ground state. This supports an increase in dipole moment upon photonic excitation. The observed redshift of the absorption maximum with increasing acceptor strength can be interpreted according to Dewar's qualitative prediction rules on the HOMO-LUMO energy gap based upon perturbation theory [26]. The p-aryl substituent is located at the unmarked 4position of the conjugated merocyanine, i.e. 7-diethylamino substituted coumarin, and should therefore lower the LUMO energy, and as a consequence cause a bathochromic shift by reducing the HOMO-LUMO energy gap. The substituent effect on fluorescence quantum yields Φf was investigated in three consanguineous series (Fig. 3). The coumarin chromophore first with TMS-ethynyl (R2 = SiMe3) and then phenylethynyl (R2 = Ph) substitution in 4-position was considered for variable R1 substituents ranging from electron-rich (R1 = NEt2, OMe) to electroneutral (R1 = H). In both series an increase of the fluorescence quantum yield with increasing donor strength of R1 is apparent (Fig. 3a). Correlation of Φf with the σp parameters of substituents R1 suggests that also fluorescence quantum yields follow this transmission pathway in the coumarin chromophore. The third series of 7-diethylamino substituted 4-arylethynyl coumarins 3j (R2 = p-NCC6H4), 3k (R2 = p-MeO2CC6H4), 3l (R2 = Ph), and 3m (R2 = p-MeOC6H4) reveals an excellent correlation of the fluorescence quantum yields Φf with σp (Fig. 3b). For gaining more insight into the nature of the vibrationally relaxed excited state a solvatochromicity study of compound 3k (R1 = NEt2, R2 = p-MeO2CC6H4) was performed. Absorption and emission maxima of compound 3k were determined in cyclohexane, tetrahydrofuran, methanol and acetonitrile (Fig. 4). The increase of solvent polarity

Fig. 3. Hammett-Taft correlations of the fluorescence quantum yield Φf in three consanguineous series (determined in dichloromethane solution with coumarin 153 as a standard in ethanol (Φf = 0.55) [23] or with 9,10-diphenylanthracene as a standard in cyclohexane (Φf = 1) [24]). a) Variation of the alkynyl substituent R2 (R2 = SiMe3, blue line; R2 = Ph; red line) with electron-rich substituents on the 7-position of the coumarin (R2 = SiMe3, R1 = NEt2 (3i), OMe (3g), H (3a). b) Variation of the remote electronic substituent effect on R2 of 3j (R1 = NEt2, R2 = p-NCC6H4), 3k (R1 = NEt2, R2 = p-MeO2CC6H4), 3l (R1 = NEt2, R2 = Ph), and 3m (R1 = NEt2, R2 = p-MeOC6H4). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 4. Solvatochromism (absorption (solid) and emission (dashed) spectra) of compound 3k (T = 293 K, λexc = λabs).

359

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causes a bathochromic shift of the absorption (cyclohexane: 392 nm; methanol: 421 nm) as well as the emission maximum (cyclohexane: 447 nm; methanol: 535 nm), a positive solvatochromism. Using Lippert-Mataga plot [27], the linear correlation of the Stokes shifts Δν̃ with the solvent orientation polarizability Δf gives a good fit (r2 = 0.9827). The change of dipole moment from ground to excited state can be calculated using the Lippert-Mataga equation (1),

v˜a

v˜e =

4

2 f (µE 3 0 hca

µG ) 2 + const

(1)

where Δν̃ a and Δν̃ b are the absorption and emission maxima (in cm−1), ε0 is the vacuum permittivity constant (8.8542 · 10−12AsV−1m−1), c is the speed of light (2.9979 · 1010 cms−1), h is the Planck's constant (6.6256 · 10−34Js−1), and the orientation polarizability Δf. It is defined by equation (2),

f=

1 2r+1 r

n2 1 2n2 + 1

(2)

with the relative permittivity εr and the optical refractive index n of the corresponding solvent (for details, see Supp Inf). The Onsager radius a was calculated from the optimized ground state structure of compound 3k by DFT calculations [28]. The change in dipole moment Δμ from ground to vibrationally relaxed excited state is calculated to 11.2 D (3.743 × 10−29) using an Onsager radius of 6.01 Å (6.01 × 10−10 m). As already mentioned the absorption and emission data of dyes bearing strongly electron donating substituents at R2 (compounds 3f, 3n, and 3o) cannot be interpreted by correlation studies. Apparently the strong electron donor changes the underlying chromophore from the coumarin to the alkynyl coumarin. A similar behavior was recently scrutinized for N,N-dimethylaminophenyl substituted coumarin merocyanines19 and for 3-piperazinyl propenylidene indolone merocyanines [29]. Here, in the consanguineous series of 3j-n the absorption maximum of the dimethylamino substituted dye 3n (400 nm) is shifted bathochromically in comparison to the electroneutral phenyl derivative 3l (420 nm), whereas the cyano substituted dye 3j (433 nm) is shifted bathochromically (Table 1, entries 10, 12, and 14). In addition, the molar decadic extinction coefficient ε of the dimethylamino substituted dye 3n (48000 ᴍ−1cm−1) is considerably higher than those of the other derivatives in this series. The fluorescence maxima are blueshifted accordingly from 3j (541 nm) over 3l (508 nm) to 3n (500 nm), however, the fluorescence quantum yield Φf of compound 3n (0.05) is by one order of magnitude smaller than the other derivatives.

Fig. 5. Energy diagram of the frontier molecular orbitals (HOMO-1, HOMO, and LUMO) of compounds 3j-n (calculated using the PBEh1PBE/6-31G(d,p) functional and basis set applying the Polarizable Continuum Model (PCM) for dichloromethane as a solvent).

density in the coumarin part, whereas dye 3j possesses dominant coefficient density in the p-cyano phenylethynyl moiety. Indeed this altered distribution affects the absorption characteristics as shown by TD-DFT calculation of dyes 3j and 3n (Table 2). The calculated values nicely reproduce the experimentally determined absorption maxima. The longest wavelength absorption maximum of compound 3l dominantly consists of the HOMO-LUMO transition, which corresponds to a charge transfer from the coumarin donor to the p-cyano phenylethynyl acceptor, with a lower degree of orbital overlap that corresponds to the numerically smaller oscillatory strength. In contrast the longest wavelength absorption maximum of compound 3n is composed of two transitions, namely the HOMO-LUMO and the HOMO-1-LUMO transition. In this case the HOMO-LUMO transition corresponds to an intense π-π*-transition with charge transfer character from the p-dimethylamino phenylethynyl donor to the coumarin acceptor, reflected by the numerically large oscillatory strength. The minor HOMO-1 to LUMO transition corresponds to a charge transfer from the coumarin donor part to the arylethynyl moiety and the coumarin acceptor part. Interestingly, the combination of two superimposed subchromophores, p-diethylamino coumarin and arylethynyl coumarin in the α-pyrone part of the dye, furnishes peculiar absorption and emission characteristics. The former can be plausibly rationalized by considering configuration interaction, ultimately leading to increased oscillatory strength, i.e. intense absorption bands in the experimental spectra.

2.3. Calculated electronic structure For further elucidation the electronic structure of underlying chromophore system in 4-alkynyl coumarins 3j-n was investigated by DFT calculations using the PBEh1PBE functional [30] and Pople's 631G(d,p) basis set [31], applying the Polarizable Continuum Model (PCM) with dichloromethane as a solvent [32]. The optimized geometries were verified by frequency analyses of the local minima. The calculated frontier molecular orbital energies (HOMO-1, HOMO, LUMO) reveal that with increasing donor strength at the pposition of substituent R2 the energy difference between HOMO-1 and HOMO considerably decreases (Fig. 5). As a consequence, a significant contribution of transitions from HOMO-1 in the absorption behavior of compound 3n (R1 = NEt2, R2 = p-Me2NC6H4) can be expected. In comparison to the acceptor substituted derivative 3j (R1 = NEt2, R2 = p-NCC6H4) the electronic structure of both HOMOs considerably differ with respect to the localization of the coefficient densities, while the LUMOs are quite similar (Fig. 6). The coefficient density of the HOMO of acceptor-substituted dye 3j is primarily localized in the coumarin part of the molecule, where in the HOMO of the donor-substituted dye 3n bears coefficient density largely in the p-dimethylamino phenylethynyl moiety. The situation conversely inverts for the electronic structure of both HOMO-1. Here dye 3n bears the coefficient

3. Conclusion In summary 16 examples of novel 4-alkynyl coumarin derivatives with tunable and intense fluorescence were synthesized, some with fluorescence quantum yields of up to 94%. The photophysical data were analyzed and rationalized by establishing structure-property relationships for consanguineous series applying Hammett-Taft correlations. Furthermore, the electronic states were rationalized by DFT and TDDFT calculations. The title compounds indeed possess superimposed subchromophores with substituent depended energy levels of the HOMO-1 and HOMO levels that can be addressed by suitable donor substitution, causing altered absorption characteristics in comparison to acceptor substituted derivatives. From solvatochromicity studies of one of the most intensively fluorescent derivatives the strongly polar excited state and the change in dipole moment (Δμ = 11.2 D) were 360

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Fig. 6. Kohn-Sham frontier molecular orbitals HOMO, HOMO-1 and LUMO of compounds 3n (left) and 3j (right) (calculated using the PBEh1PBE/6-31G(d,p) functional and basis set applying the Polarizable Continuum Model (PCM) for dichloromethane as a solvent). Table 2 TD-DFT calculations of the absorption maxima for the compounds 3j and 3n. (calculated using the PBEh1PBE/6-31G(d,p) functional and basis set applying the Polarizable Continuum Model (PCM) for dichloromethane as a solvent). λmax,abs [nm] (ε [L mol 3j

−1

cm

−1

λmax,calcd [nm]

Most dominant contributions

Oscillator strength

453 330

HOMO → LUMO (98%) HOMO-1 → LUMO (82%) HOMO → LUMO+1 (16%) HOMO-2 → LUMO (95%) HOMO → LUMO+1 (2%) HOMO → LUMO (58%) HOMO-1 → LUMO (41%) HOMO-1 → LUMO (58%) HOMO → LUMO (41%) HOMO-2 → LUMO (90%) HOMO-3 → LUMO (5%) HOMO-1 → LUMO+3 (2%) HOMO-1 → LUMO +1 (2%)

0.211 1.002

a

])

433 (13600) 311 (30600)

326 3n

400 (48000)

408 383

281 (28300)

a

299

0.183 1.046 0.370 0.015

Recorded in dichloromethane, T = 293 K, c(3) = 10−4 M.

assessed by Lippert-Mataga analysis. With this experimental and theoretical study the stage is set for developing coumarin based polarity sensitive fluorescence probes and the development of fine-tunable luminophores is currently underway.

Mass spectra were recorded with a triple-quadrupole mass spectrometer (Finnigan MAR) or the ESI Ion-Trap-API-mass spectrometer Finnigan LCQ Deca (Thermo Quest). High resolution mass spectra were measured with a UHR-QTOF maxis 4G (Bruker Daltonics). Infrared spectra were recorded with a Shimadzu IR Affinity-1 with ATR technique. The intensities of signals are abbreviated as s (strong), m (medium) and w (weak). Absorption spectra were recorded in CH2Cl2 at 298 K on Perkin Elmer UV/VIS/NIR Lambda 19 Spectrometer. Emission spectra were recorded in CH2Cl2 at 298 K on a Hitachi F7000 spectrometer. DFT calculations were performed using the PBEh1PBE functional [30] and Pople's 6-31G(d,p) basis set [31], applying the Polarizable Continuum Model (PCM) with dichloromethane as a solvent [32]. The optimized geometries were verified by frequency analyses of the local minima.

4. Experimental 4.1. General considerations All reactions were carried out in Schlenk tubes or microwave vials under a nitrogen atmosphere. Solvents were dried by a solvent purification system (MBraun system MB-SPS-800). Dielectric heating was performed in a single mode microwave cavity producing continuous irradiation at 2450 MHz. Further purification of the compounds was performed by flash column chromatography (silica gel 60, mesh 230–400, MN). TLC: silica coated aluminium plates (60, F254, Merck).1H, 13C, DEPT and NOESY NMR spectra were recorded in CDCl3 (1H δ 7.26, 13C δ 77.2) or DMSO‑d6 (1H δ 2.50, 13C δ 39.52) on 300 MHz (Bruker AVIII) or 600 MHz (BrukerAvance III-600) NMR spectrometers. The assignments of Cquat, CH, CH2 and CH3 nuclei were based on DEPT spectra. The elemental analyses were carried out in the microanalytical laboratory on a Perkin Elmer Series II Analyser 2400 of the Pharmazeutisches Institut of the Heinrich-Heine-Universität Düsseldorf.

4.2. General procedure for the synthesis of coumaryl alkynes 3 In a microwave tube PdCl2(PPh3)2 (14.0 mg, 0.02 mmol) and CuI (8.00 mg, 0.04 mmol) were dissolved in THF (1.00 mL) under nitrogen. Triflate 1 (1.00 equiv.) and alkyne 2 (1.00 equiv) were subsequently added to the reaction mixture (for experimental details, see Table 3). Finally, triethylamine (0.14 mL, 1.00 equiv) was added. The reaction mixture turned from yellow to black and was stirred at room temp for 1 h. The solvents were removed in vacuo and the crude product was 361

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Table 3 Experimental details for the synthesis of coumaryl alkynes 3. entry

coumaryl triflates 1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

147 mg 294 mg 294 mg 147 mg 147 mg 147 mg 162 mg 162 mg 180 mg 180 mg 180 mg 180 mg 180 mg 180 mg 180 mg 143 mg

(0.50 mmol) (1.00 mmol) (1.00 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.50 mmol) (0.39 mmol)

of of of of of of of of of of of of of of of of

1a 1a 1a 1a 1a 1a 1b 1b 1c 1c 1c 1c 1c 1c 1c 1c

alkyne 2

coumaryl alkynes 3 (yield)

70 mg (0.68 mmol) of TMSacetylene (2a) 66 mg (1.0 mmol) of cyclopropylacetylene (2b) 68 mg (1.0 mmol) of 1-pentyne (2c) 51 mg (0.5 mmol) of phenylacetylene (2d) 67 mg (0.5 mmol) of 1-ethynyl-4-methoxybenzene (2e) 73 mg (0.5 mmol) of 4-ethynyl-N,N-dimethylaniline (2f) 70 mg (0.68 mmol) of TMSacetylene (2a) 51 mg (0.5 mmol) of phenylacetylene (2d) 70 mg (0.68 mmol) of TMSacetylene (2a) 64 mg (0.5 mmol) of 4-ethynylbenzonitrile (2g) 80 mg (0.5 mmol) of methyl 4-ethynylbenzoate (2h) 51 mg (0.5 mmol) of phenylacetylene (2d) 70 mg (0.53 mmol) of 1-ethynyl-4-methoxybenzene (2e) 73 mg (0.5 mmol) of 4-ethynyl-N,N-dimethylaniline (2f) 119 mg (0.50 mmol) of 3-ethynyl-10-methyl-10H-phenothiazine (2i) 115 mg (0.39 mmol) of 3-ethynyl-1-tosyl-1H-indole (2j)

100 mg 185 mg 170 mg 110 mg 120 mg 130 mg 120 mg 130 mg 155 mg 162 mg 184 mg 130 mg 139 mg 145 mg 178 mg 174 mg

4.2.1. 4-((Trimethylsilyl)ethynyl)-2H-chromen-2-one (3a) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 10:1) compound 3a (100 mg, 83%) was obtained as a beige solid, Mp 130 °C; Rf (n-hexane/ethyl acetate 10:1) = 0.40. 1H NMR (600 MHz, CDCl3): δ 0.33 (s, 9 H), 6.55 (s, 1 H), 7.35–7.29 (m, 2 H), 7.59–7.52 (m, 1 H), 7.84 (dd, J = 7.8, 1.6 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ −0.3 (CH3), 97.6 (Cquat), 109.7 (Cquat), 117.1 (CH), 118.4 (Cquat), 119.3 (CH), 124.6 (CH), 126.8 (CH), 132.4 (CH), 137.0 (Cquat), 153.7 (Cquat), 160.3 (Cquat). EI-MS (70 eV, m/z (%)): 242 (44, [M+]), 228 (19), 227 (100, [C H O Si+]), 199 (16), 175 (19). IR: ν̃ 11

of of of of of of of of of of of of of of of of

3a 3b 3c 3d 3e 3f 3g 3h 3i 3j 3k 3l 3m 3n 3o 3p

7.85 (dd, J = 8.2, 1.6 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ 13.8 (CH3), 21.9 (CH2), 21.9 (CH2), 75.1 (Cquat), 105.0 (Cquat), 117.0 (CH), 118.4 (CH), 119.0 (Cquat), 124.5 (CH), 126.9 (CH), 132.2 (CH), 138.2 (Cquat), 153.7 (Cquat), 160.6 (Cquat). EI-MS (70 eV, m/z (%)): 213 (12), 212 (77, [M+]), 184 (34), 183 (100, [C12H7O2+]), 169 (32, [C11H5O2+]), 156 (12), 155 (49, [C12H11+]), 141 (11), 128 (13), 127 (19), 126 (11). IR: ν̃ [cm−1] = 3061 (w), 3042 (w), 2961 (w), 2932 (w), 2872 (w), 2251 (w), 2224 (w), 2205 (w), 1746 (w), 1705 (s), 1699 (s), 1674 (m), 1603 (m), 1555 (m), 1487 (w), 1464 (w), 1449 (m), 1371 (m), 1325 (w), 1279 (w), 1256 (m), 1229 (w), 1213 (w), 1179 (m), 1138 (w), 1101 (m), 1032 (w), 995 (w), 928 (m), 878 (w), 854 (s), 810 (w), 775 (s), 750 (s), 710 (w), 694 (w), 656 (m), 633 (w), 613 (w). Anal. calcd. for C14H12O2 (212.1): C 79.23, H 5.70; Found: C 79.04, H 5.50.

purified by flash chromatography on silica gel to give the desired coumaryl alkyne 3.

13

(83%) (88%) (80%) (90%) (87%) (90%) (88%) (94%) (99%) (95%) (98%) (82%) (80%) (80%) (79%) (87%)

2

[cm−1] = 2990 (w), 2963 (w), 2901 (w), 1751 (w), 1724 (m), 1601 (w), 1556 (w), 1483 (w), 1450 (w), 1427 (w), 1375 (w), 1362 (m), 1325 (w), 1303 (w), 1273 (w), 1248 (m), 1211 (w), 1180 (w), 1175 (w), 1130 (w), 1076 (w), 1059 (m), 1047 (w), 1030 (w), 931 (m), 856 (m), 843 (s), 795 (w), 756 (m), 746 (m), 706 (w), 688 (m), 642 (w), 623 (w). Anal. calcd. for C14H14O2Si (242.1): C 69.39, H 5.82; Found: C 69.52, H 5.97.

4.2.4. 4-(Phenylethynyl)-2H-chromen-2-one (3d) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 5:1) compound 3d (110 mg, 90%) was obtained as a beige solid, Mp 134 °C (dec.); Rf (n-hexane/ethyl acetate 5:1) = 0.20. 1H NMR (600 MHz, CDCl3): δ 6.63 (s, 1H), 7.38–7.33 (m, 2 H), 7.49–7.42 (m, 3 H), 7.58 (ddd, J = 8.8, 7.4, 1.6 Hz, 1 H), 7.67–7.62 (m, 2 H), 7.96 (dd, J = 8.3, 1.6 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ 82.9 (Cquat), 102.3 (Cquat), 117.2 (CH), 118.5 (Cquat), 118.5 (Cquat), 121.3 (Cquat), 124.6 (CH), 126.8 (CH), 128.9 (CH), 130.4 (CH), 132.4 (CH), 132.4 (CH), 137.4 (Cquat), 153.7 (Cquat), 160.4 (Cquat). EI-MS (70 eV, m/z (%)): 247 (19), 246 (100, [M+]), 218 (52, [C16H10O+]), 202 (13, [C16H10+]), 190 (10), 189 (48), 95 (10), 94 (16). IR: ν̃ [cm−1] = 3073 (w), 3048 (w), 2965 (w), 2236 (w), 2203 (m), 1796 (w), 1751 (w), 1719 (s), 1607 (m), 1555 (m), 1487 (w), 1448 (w), 1441 (w), 1412 (w), 1371 (m), 1325 (w), 1283 (w), 1271 (m), 1250 (m), 1188 (m), 1184 (m), 1176 (m), 1173 (m), 1142 (w), 1125 (m), 1096 (w), 1070 (w), 1044 (w), 1032 (w), 997 (w), 954 (w), 934 (m), 912 (w), 856 (m), 852 (m), 773 (m), 768 (s), 754 (s), 748 (s), 746 (s), 708 (m), 685 (s), 669 (w), 658 (m), 615 (w). Anal. calcd. for C17H10O2 (246.1): C 82.91, H 4.09; Found: C 82.62, H 4.25.

4.2.2. 4-(Cyclopropylethynyl)-2H-chromen-2-one (3b) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 4:1) compound 3b (185 mg, 88%) was obtained as a beige solid, Mp 109 °C (dec.); Rf (n-hexane/ethyl acetate 4:1) = 0.30. 1H NMR (600 MHz, CDCl3): δ 0.99–0.95 (m, 2 H), 1.08–1.02 (m, 2 H), 1.60 (tt, J = 8.3, 5.0 Hz, 1 H), 6.44 (s, 1 H), 7.31–7.27 (m, 2 H), 7.56–7.47 (m, 1 H), 7.79 (dd, J = 8.1, 1.6 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ 0.8 (CH3), 9.8 (CH2), 70.3 (Cquat), 108.7 (Cquat), 117.0 (CH), 118.0 (CH), 118.9 (Cquat), 124.4 (CH), 126.8 (CH), 132.2 (CH), 138.1 (Cquat), 153.6 (Cquat), 160.6 (Cquat). EI-MS (70 eV, m/z (%)): 211 (12), 210 (80, [M+]), 184 (10), 182 (44, [C12H6O2+]), 181 (100), 154 (15), 153 (25, [C12H9+]), 152 (33), 126 (34), 76 (13), 43 (10). IR: ν̃ [cm−1] = 3084 (w), 3063 (w), 2214 (m), 1705 (s), 1678 (m), 1645 (w), 1601 (s), 1553 (m), 1485 (w), 1447 (m), 1435 (w), 1379 (m), 1348 (m), 1323 (m), 1275 (w), 1254 (m), 1204 (w), 1179 (s), 1153 (w), 1140 (m), 1121 (m), 1084 (w), 1055 (w), 1030 (m), 926 (s), 874 (w), 860 (s), 814 (m), 799 (w), 775 (s), 746 (s), 712 (m), 696 (w), 652 (m), 629 (w),610 (m). Anal. calcd. for C14H10O2 (210.1): C 79.98, H 4.79; Found: C 79.76, H 4.67.

4.2.5. 4-((4-Methoxyphenyl)ethynyl)-2H-chromen-2-one (3e) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 5:1) compound 3e (120 mg, 87%) was obtained as a light yellow solid, Mp 140 °C; Rf (n-hexane/ethyl acetate 5:1) = 0.16. 1H NMR (600 MHz, DMSO‑d6): δ 3.84 (s, 3 H), 6.72 (s, 1 H), 7.07 (d, J = 8.8 Hz, 2 H), 7.37–7.51 (m, 2 H), 7.69 (ddd, J = 8.5, 7.4, 1.6 Hz, 1 H), 7.72 (d, J = 8.8 Hz, 2 H), 8.02 (dd, J = 7.9, 1.6 Hz, 1 H). 13C NMR (151 MHz, DMSO‑d6): δ 55.5 (CH3), 99.5 (Cquat), 102.7 (Cquat), 112.1 (Cquat), 114.7 (CH), 116.7 (CH), 117.6 (CH), 117.8 (Cquat), 124.9 (CH), 126.6 (CH), 132.7 (CH), 134.3 (CH), 136.4 (Cquat), 153.0 (Cquat), 159.2 (Cquat), 161.1 (Cquat). EI-MS (70 eV, m/z (%)): 277 (20), 276 (100,

4.2.3. 4-(Pent-1-yn-1-yl)-2H-chromen-2-one (3c) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 5:1) compound 3c (170 mg, 80%) was obtained as a beige solid, Mp 96 °C (dec.); Rf (n-hexane/ethyl acetate 5:1) = 0.30. 1H NMR (600 MHz, CDCl3): δ 1.10 (t, J = 7.4 Hz, 3 H), 1.73 (sext, J = 7.2 Hz, 2 H), 2.55 (t, J = 7.0 Hz, 2 H), 7.35–7.26 (m, 2 H), 7.59–7.45 (m, 1 H), 362

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[M+]), 262 (11), 261 (51, [C17H9O3+]), 233 (13), 205 (30), 176 (16). IR: ν̃ [cm−1] = 3003 (w), 2955 (w), 2899 (w), 2843 (w), 2203 (m), 1881 (w), 1803 (w), 1701 (s), 1693 (s), 1681 (m), 1645 (w), 1597 (s), 1560 (m), 1555 (m), 1510 (m), 1464 (w), 1450 (m), 1439 (m), 1418 (s), 1379 (m), 1361 (w), 1298 (m), 1260 (m), 1246 (m), 1182 (m), 1173 (s), 1124 (m), 1107 (m), 1059 (w), 1042 (m), 1022 (s), 989 (w), 937 (s), 866 (m), 847 (s), 827 (s), 802 (m), 768 (s), 748 (s), 708 (m), 692 (w), 644 (m), 610 (m). Anal. calcd. for C18H12O3 (276.1): C 78.25, H 4.38; Found: C 78.11, H 4.23.

1443 (w), 1435 (w), 1423 (w), 1418 (w), 1381 (s), 1346 (w), 1284 (m), 1257 (m), 1213 (m), 1190 (w), 1150 (m), 1126 (m), 1107 (w), 1097 (w), 1067 (m), 1047 (m), 1026 (m), 1020 (m), 997 (w), 986 (m), 914 (w), 879 (m), 841 (m), 818 (m), 808 (m), 760 (m), 748 (w), 710 (m), 687 (m), 667 (w), 650 (m), 617 (w). Anal. calcd. for C18H12O3 (276.1): C 78.25, H 4.38; Found: C 78.11, H 4.23. 4.2.9. 7-(Diethylamino)-4-((trimethylsilyl)ethynyl)-2H-chromen-2-one (3i) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 10:1) compound 3i (155 mg, 99%) was obtained as an orange solid, Mp 118 °C; Rf (n-hexane/ethyl acetate 10:1) = 0.20. 1H NMR (600 MHz, CDCl3): δ 0.30 (s, 9 H), 1.20 (t, J = 7.1 Hz, 6 H), 3.41 (q, J = 7.1 Hz, 4 H), 6.16 (s, 1 H), 6.45 (d, J = 2.5 Hz, 1 H), 6.61 (dd, J = 8.9, 2.5 Hz, 1 H), 7.58 (d, J = 8.9 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ −0.2 (CH3), 12.6 (CH3), 45.0 (CH2), 97.6 (CH), 98.6 (Cquat), 107.4 (Cquat), 108.1 (Cquat), 109.0 (CH), 112.0 (CH), 127.7 (CH), 137.1 (Cquat), 151.0 (Cquat), 156.3 (Cquat), 161.7 (Cquat). EI-MS (70 eV, m/z (%)): 313 (29, [M+]), 299 (25), 298 (100, [C17H20NO2Si+]), 270 (12, [C15H15NO2Si+]), 142 (15). IR: ν̃ [cm−1] = 2967 (w), 2930 (w), 2901 (w), 1728 (w), 1713 (w), 1709 (w), 1682 (w), 1614 (w), 1582 (w), 1574 (w), 1558 (w), 1539 (w), 1520 (w), 1472 (w), 1446 (w), 1414 (w), 1375 (w), 1360 (w), 1340 (w), 1298 (w), 1285 (w), 1269 (w), 1248 (w), 1225 (w), 1213 (w), 1196 (w), 1167 (w), 1148 (w), 1078 (w), 1072 (w), 1059 (w), 1013 (w), 860 (w), 843 (s), 824 (w), 800 (w), 762 (w), 739 (w), 710 (w), 650 (w), 640 (w), 613 (w). Anal. calcd. for C18H23NO2Si (313.2): C 68.97, H 7.40, N 4.47; Found: C 69.09, H 7.70, N 4.37.

4.2.6. 4-((4-(Dimethylamino)phenyl)ethynyl)-2H-chromen-2-one (3f) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 2:1) compound 3f (130 mg, 90%) was obtained as a tan solid, Mp 155 °C; Rf (n-hexane/ethyl acetate 2:1) = 0.29. 1H NMR (600 MHz, DMSO‑d6): δ 3.00 (s, 6 H), 6.59 (s, 1 H), 6.76 (d, J = 8.9 Hz, 2 H), 7.477.41 (m, 2 H), 7.56 (d, J = 8.9 Hz, 2 H), 7.67 (ddd, J = 8.5, 7.3, 1.7 Hz, 1 H), 8.00 (dd, J = 7.9, 1.6 Hz, 1 H). 13C NMR (151 MHz, DMSO‑d6): δ 39.6 (CH3), 82.3 (Cquat), 105.7 (Cquat), 105.7 (Cquat), 111.8 (CH), 115.7 (CH), 116.7 (CH), 117.9 (Cquat), 124.8 (CH), 126.6 (CH), 132.5 (CH), 133.9 (CH), 136.9 (Cquat), 151.3 (Cquat), 153.0 (Cquat), 159.4 (Cquat). EIMS (70 eV, m/z (%)): 290 (21), 289 (100, [M+]), 288 (15), 276 (11), 261 (11, [C18H15NO+]), 260 (13), 218 (21), 190 (15), 189 (15), 130 (15), 120 (15, [C8H10N+]). IR: ν̃ [cm−1] = 3069 (w), 2961 (w), 2887 (w), 2795 (w), 2197 (m), 1705 (s), 1682 (m), 1647 (w), 1601 (s), 1555 (m), 1518 (m), 1477 (m), 1439 (m), 1406 (w), 1360 (m), 1325 (m), 1290 (w), 1275 (m), 1248 (m), 1227 (m), 1202 (m), 1182 (s), 1165 (m), 1144 (m), 1123 (m), 1059 (m), 1042 (m), 1032 (m), 1003 (w), 936 (s), 934 (s), 891 (m), 864 (m), 810 (s), 770 (m), 750 (s), 716 (m), 689 (m), 638 (m). Anal. calcd. for C19H15NO2 (259.1): C 78.87, H 5.23, N 4.84; Found: C 78.60, H 5.39, N 4.68.

4.2.10. 4-((7-(Diethylamino)-2-oxo-2H-chromen-4-yl)ethynyl)benzonitrile (3j) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 3:1) compound 3j (162 mg, 95%) was obtained as an orange solid, Mp 167 °C; Rf (n-hexane/ethyl acetate 3:1) = 0.21. 1H NMR (600 MHz, CDCl3): δ 1.22 (t, J = 7.1 Hz, 6 H), 3.43 (q, J = 7.1 Hz, 4 H), 6.26 (s, 1 H), 6.50 (d, J = 2.5 Hz, 1 H), 6.64 (dd, J = 9.0, 2.5 Hz, 1 H), 7.63 (d, J = 8.9 Hz, 1 H), 7.70 (s, 4 H). 13C NMR (151 MHz, CDCl3): δ 12.5 (CH3), 45.1 (CH2), 87.4 (Cquat), 97.6 (Cquat), 97.8 (CH), 107.8 (Cquat), 109.1 (CH), 112.2 (CH), 113.2 (Cquat), 118.2 (Cquat), 126.5 (Cquat), 127.4 (CH), 132.4 (CH), 132.7 (CH), 136.3 (Cquat), 151.2 (Cquat), 156.3 (Cquat), 161.3 (Cquat). EI-MS (70 eV, m/z (%)): 343 (10), 342 (39, [M+]), 328 (23), 327 (100, [C21H15N2O2+]), 299 (20, [C19H10N2O2+]), 252 (12, [C16H14NO2+]), 149 (12), 43 (30). IR: ν̃ [cm−1] = 3092 (w), 2967 (w), 2226 (w), 2212 (w), 1709 (s), 1674 (w), 1620 (s), 1603 (m), 1587 (m), 1558 (w), 1533 (w), 1526 (m), 1506 (w), 1497 (m), 1470 (w), 1450 (w), 1414 (m), 1400 (m), 1383 (m), 1367 (w), 1358 (m), 1339 (m), 1298 (w), 1284 (w), 1275 (w), 1263 (m), 1227 (w), 1194 (w), 1177 (w), 1163 (w), 1138 (m), 1105 (w), 1090 (w), 1076 (w), 1069 (w), 1042 (w), 1013 (w), 984 (w), 899 (w), 847 (m), 829 (s), 824 (s), 793 (m), 772 (w), 706 (w), 648 (w), 636 (w). Anal. calcd. for C22H18N2O2 (342.1): C 77.17, H 5.30, N 8.18; Found: C 76.89, H 5.33, N 8.06.

4.2.7. 7-Methoxy-4-((trimethylsilyl)ethynyl)-2H-chromen-2-one (3g) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 10:1) compound 3g (120 mg, 88%) was obtained as a white solid, Mp 131 °C; Rf (n-hexane/ethyl acetate 10:1) = 0.23. 1H NMR (600 MHz, CDCl3): δ 0.32 (d, J = 0.7 Hz, 9 H), 3.87 (s, 3 H), 6.38 (s, 1 H), 6.78 (d, J = 2.5 Hz, 1 H), 6.88 (dd, J = 8.8, 2.5 Hz, 1 H), 7.70 (d, J = 8.7 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ −0.3 (CH3), 55.9 (CH3), 97.9 (Cquat), 100.9 (CH), 108.9 (Cquat), 112.1 (Cquat), 112.7 (CH), 115.9 (CH), 127.8 (CH), 137.0 (Cquat), 155.5 (Cquat), 160.7 (Cquat), 163.3 (Cquat). EI-MS (70 eV, m/z (%)): 273 (15), 272 (66, [M+]), 258 (19), 257 (100, [C14H13O3Si+]), 229 (31, [C14H16OSi+]), 205 (13), 129 (10), 115 (13). IR: ν̃ [cm−1] = 2963 (w), 2843 (w), 1767 (w), 1755 (w), 1717 (m), 1614 (m), 1605 (m), 1553 (w), 1506 (w), 1422 (w), 1367 (m), 1342 (w), 1281 (m), 1257 (w), 1244 (m), 1209 (m), 1146 (m), 1134 (m), 1068 (w), 1022 (m), 986 (m), 878 (m), 843 (s), 831 (s), 820 (s), 797 (m), 768 (m), 741 (w), 727 (m), 710 (w), 689 (w), 642 (m), 621 (w). Anal. calcd. for C15H16O3Si (272.1): C 66.15, H 5.92; Found: C 66.32, H 6.32. 4.2.8. 7-Methoxy-4-(phenylethynyl)-2H-chromen-2-one (3h) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 10:1) compound 3h (130 mg, 94%) was obtained as a white solid, Mp 151 °C; Rf (n-hexane/ethyl acetate 10:1) = 0.16. 1H NMR (600 MHz, CDCl3): δ 3.89 (s, 3 H), 6.46 (s, 1 H), 6.82 (d, J = 2.5 Hz, 1 H), 6.91 (dd, J = 8.8, 2.5 Hz, 1 H), 7.51–7.36 (m, 3 H), 7.63 (dt, J = 6.7, 1.6 Hz, 2 H), 7.83 (d, J = 8.7 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ 56.0 (CH3), 83.2 (Cquat), 100.9 (CH), 101.7 (Cquat), 112.2 (Cquat), 112.8 (CH), 115.2 (CH), 121.4 (Cquat), 127.8 (CH), 128.8 (CH), 130.2 (CH), 132.3 (CH), 137.4 (Cquat), 155.5 (Cquat), 160.8 (Cquat), 163.3 (Cquat). EI-MS (70 eV, m/z (%)): 277 (23), 276 (100, [M+]), 248 (45, [C17H12O2+]), 233 (31), 205 (14), 176 (20, [C10H7O3+]), 124 (10), 88 (14). IR: ν̃ [cm−1] = 3061 (w). 2986 (w), 2972 (w), 2941 (w), 2901 (w), 2845 (w), 2212 (w), 1713 (s), 1682 (w), 1674 (w), 1668 (w), 1645 (w), 1639 (w), 1605 (m), 1591 (m), 1568 (w), 1558 (w), 1549 (w), 1539 (w), 1531 (w), 1504 (w), 1489 (m), 1464 (w), 1452 (w),

4.2.11. Methyl 4-((7-(diethylamino)-2-oxo-2H-chromen-4-yl)ethynyl) benzoate (3k) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 5:1) compound 3k (184 mg, 98%) was obtained as an orange solid, Mp 158 °C; Rf (n-hexane/ethyl acetate 5:1) = 0.11. 1H NMR (600 MHz, CDCl3): δ 1.22 (t, J = 7.1 Hz, 6 H), 3.43 (q, J = 7.1 Hz, 4 H), 3.95 (s, 3 H), 6.26 (s, 1 H), 6.50 (d, J = 2.5 Hz, 1 H), 6.65 (dd, J = 9.1, 2.5 Hz, 1 H), 7.74-7.60 (m, 3 H), 8.08 (d, J = 8.4 Hz, 2 H). 13C NMR (151 MHz, CDCl3): δ 12.6 (CH3), 45.2 (CH2), 52.5 (CH3), 86.2 (Cquat), 97.9 (CH), 99.0 (Cquat), 108.0 (Cquat), 109.1 (CH), 111.9 (CH), 126.2 (Cquat), 127.6 (CH), 129.8 (CH), 131.0 (Cquat), 132.2 (CH), 136.8 (Cquat), 151.1 (Cquat), 156.3 (Cquat), 161.5 (Cquat), 166.4 (Cquat). EI-MS (70 eV, m/z (%)): 376 (11), 375 (44, [M+]), 361 (25), 360 (100, 363

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[C22H18NO4+]), 332 (13, [C20H13NO4+]), 165 (35), 150 (20), 109 (13). IR: ν̃ [cm−1] = 3115 (w), 3065 (w), 2968 (w), 2949 (w), 2222 (w), 2208 (w), 1718 (m), 1701 (s), 1670 (w), 1664 (w), 1655 (w), 1618 (m), 1605 (m), 1578 (m), 1539 (w), 1522 (m), 1503 (w), 1491 (w), 1483 (w), 1474 (w), 1458 (w), 1452 (w), 1429 (w), 1416 (m), 1383 (m), 1358 (m), 1350 (m), 1308 (w), 1275 (m), 1227 (m), 1217 (m), 1192 (w), 1173 (w), 1134 (m), 1107 (m), 1095 (m), 1078 (m), 1047 (w), 1040 (m), 1026 (w), 1016 (m), 984 (w), 970 (w), 943 (w), 901 (w), 889 (w), 858 (m), 839 (w), 825 (m), 810 (w), 797 (m), 768 (s), 741 (w), 712 (w), 692 (m), 669 (w), 648 (w), 640 (w), 615 (m). Anal. calcd. for C23H21O4 (375.1): C C 73.58, H 5.64, N 3.73; Found: C 73.32, H 5.75, N 3.84.

45.2 (CH2), 83.0 (Cquat), 97.6 (CH), 103.5 (Cquat), 108.0 (Cquat), 108.4 (Cquat), 108.7 (CH), 109.8 (CH), 111.8 (CH), 127.8 (CH), 133.8 (CH), 138.3 (Cquat), 150.9 (Cquat), 151.2 (Cquat), 156.2 (Cquat), 162.1 (Cquat). EI-MS (70 eV, m/z (%)): 361 (23), 360 (92, [M+]), 346 (25), 345 (100, [C22H21N2O2+]), 317 (12), 316 (22, [C21H18NO2+]), 173 (48), 158 (44), 144 (18, [C10H10N+]), 116 (15), 70 (10), 61 (11). IR: ν̃ [cm−1] = 2974 (w), 2920 (w), 2860 (w), 2187 (m), 1686 (m), 1601 (m), 1582 (s), 1530 (m), 1514 (m), 1485 (w), 1464 (w), 1447 (w), 1393 (m), 1364 (m), 1342 (m), 1296 (w), 1277 (w), 1265 (m), 1229 (m), 1182 (m), 1153 (m), 1123 (m), 1070 (m), 1042 (m), 999 (w), 984 (w), 945 (w), 928 (w), 895 (w), 860 (m), 831 (m), 814 (s), 799 (s), 783 (m), 772 (m), 746 (w), 712 (w), 694 (w), 677 (w), 656 (m), 644 (w). Anal. calcd. for C23H24N2O2 (360.2): C 76.64, H 6.71, N 7.77; Found: C 76.39, H 6.84, N 7.70.

4.2.12. 7-(Diethylamino)-4-(phenylethynyl)-2H-chromen-2-one (3l) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 3:1) compound 3l (130 mg, 82%) was obtained as an orange solid, Mp 145 °C; Rf (n-hexane/ethyl acetate 3:1) = 0.25. 1H NMR (600 MHz, DMSO‑d6): δ 1.13 (t, J = 7.0 Hz, 6 H), 3.45 (q, J = 7.0 Hz, 4 H), 6.25 (s, 1 H), 6.55 (d, J = 2.4 Hz, 1 H), 6.77 (dd, J = 9.1, 2.5 Hz, 1 H), 7. 47–7.55 (m, 3 H), 7.69–7.74 (m, 3 H). 13C NMR (151 MHz, DMSO‑d6): δ 12.3 (CH3), 44.1 (CH2), 83.4 (Cquat), 96.8 (CH), 100.1 (Cquat), 106.7 (Cquat), 109.2 (CH), 110.3 (CH), 120.6 (Cquat), 127.4 (CH), 129.0 (CH), 130.4 (CH), 132.1 (CH), 136.3 (Cquat), 150.9 (Cquat), 155.8 (Cquat), 160.1 (Cquat). EI-MS (70 eV, m/z (%)): 318 (12), 317 (51, [M+]), 303 (23), 302 (100, [C20H16NO2+), 277 (19, [C19H18NO+]), 274 (18, [C18H11NO2+]), 189 (11), 43 (10). IR: ν̃ [cm−1] = 2970 (w). 2938 (w), 2901 (w), 2687 (w), 2207 (w), 1705 (s), 1690 (m), 1580 (m), 1520 (m), 1485 (m), 1441 (w), 1410 (m), 1379 (m), 1342 (m), 1298 (m), 1281 (m), 1263 (m), 1227 (m), 1198 (m), 1177 (w), 1148 (w), 1134 (m), 1094 (m), 1080 (m), 1072 (m), 1043 (m), 1009 (w), 984 (w), 957 (w), 920 (m), 899 (w), 860 (w), 841 (m), 829 (s), 812 (m), 797 (m), 770 (w), 756 (s), 741 (w), 725 (w), 689 (s), 665 (m), 654 (m). HRMS calcd. for C21H20NO2+H+: 318.1492; Found: 318.1489.

4.2.15. 7-(Diethylamino)-4-((10-methyl-10H-phenothiazin-3-yl)ethynyl)2H-chromen-2-one (3°) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 5:1) compound 3o (178 mg, 79%) was obtained as an orange solid, Mp 222 °C; Rf (n-hexane/ethyl acetate 5:1) = 0.09.1H NMR (600 MHz, CDCl3): δ 1.25 (t, J = 7.1 Hz, 6 H), 3.43 (s, 3 H), 3.45 (q, J = 7.2 Hz, 4 H), 6.24 (s, 1 H), 6.55 (s, 1 H), 6.72 (d, J = 8.8 Hz, 1 H), 6.81 (d, J = 8.4 Hz, 1 H), 6.86 (dd, J = 8.2, 1.1 Hz, 1 H), 7.00 (td, J = 7.5, 1.2 Hz, 1 H), 7.16 (dd, J = 7.6, 1.5 Hz, 1 H), 7.22 (ddd, J = 8.2, 7.4, 1.5 Hz, 1 H), 7.38 (d, J = 1.9 Hz, 1 H), 7.43 (dd, J = 8.4, 1.9 Hz, 1 H), 7.71 (d, J = 8.9 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ 12.4 (CH3), 35.6 (CH3), 45.3 (CH2), 84.0 (Cquat), 98.1 (CH), 100.0 (Cquat), 100.6 (Cquat), 109.2 (CH), 111.0 (CH), 113.9 (CH), 114.5 (CH), 115.2 (Cquat), 122.5 (Cquat), 123.2 (CH), 123.8 (Cquat), 127.3 (CH), 127.6 (CH), 127.7 (CH), 130.4 (CH), 131.9 (CH), 137.4 (Cquat), 144.8 (Cquat), 147.3 (Cquat), 150.4 (Cquat), 156.1 (Cquat), 161.6 (Cquat). EI-MS (70 eV, m/z (%)): 454 (10), 453 (30),452 (100, [M+]), 437 (97, 422 (11, [C26H18N2O2S+]), 394 (10, [C27H21N2O2S+]), [C24H14N2O2S+]), 393 (21), 365 (11, [C23H11NO2S+]), 219 (10), 218 (46), 211 (12), 205 (22), 197 (33), 183 (11), 155 (19). IR: ν̃ [cm−1] = 2970 (w), 2928 (w), 2901 (w), 2893 (w), 2868 (w), 2201 (w), 1705 (w), 1699 (w), 1611 (w), 1601 (w), 1580 (w), 1558 (w), 1539 (w), 1516 (w), 1506 (w), 1497 (w), 1460 (w), 1443 (w), 1410 (m), 1383 (w), 1373 (w), 1358 (w), 1333 (w), 1300 (w), 1281 (w), 1259 (w), 1227 (w), 1196 (w), 1157 (w), 1146 (w), 1134 (m), 1107 (w), 1074 (w), 1057 (w), 1049 (w), 1042 (w), 1011 (w), 984 (w), 968 (w), 941 (w), 926 (w), 901 (w), 881 (w), 860 (w), 845 (w), 822 (m), 802 (w), 770 (w), 752 (m), 737 (w), 725 (w), 710 (w), 702 (w), 673 (w), 646 (w), 611 (w). Anal. calcd. for C28H24N2O2S (452.2): C 74.31, H 5.35, N 6.19, S 7.08; Found: C 74.43, H 5.53, N 6.09, S 7.05.

4.2.13. 7-(Diethylamino)-4-((4-methoxyphenyl)ethynyl)-2H-chromen-2one (3 m) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 3:1) compound 3m (139 mg, 80%) was obtained as an orange solid, Mp 161 °C; Rf (n-hexane/ethyl acetate 3:1) = 0.20. 1H NMR (600 MHz, CDCl3): δ 1.22 (t, J = 7.1 Hz, 6 H), 3.42 (q, J = 7.1 Hz, 4 H), 3.86 (s, 3 H), 6.21 (s, 1 H), 6.48 (d, J = 2.5 Hz, 1 H), 6.63 (dd, J = 9.1, 2.5 Hz, 1 H), 6.92 (d, J = 8.7 Hz, 2 H), 7.55 (d, J = 8.7 Hz, 2 H), 7.69 (d, J = 8.9 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ 12.6 (CH3), 45.0 (CH2), 55.6 (CH3), 83.0 (Cquat), 97.7 (CH), 101.2 (Cquat), 108.2 (Cquat), 108.8 (CH), 110.8 (CH), 113.8 (Cquat), 114.4 (CH), 127.7 (CH), 134.0 (CH), 137.8 (Cquat), 151.0 (Cquat), 156.3 (Cquat), 161.0 (Cquat), 161.9 (Cquat). EI-MS (70 eV, m/z (%)): 348 (13), 347 (52, [M+]), 333 (24), 332 (100, [C21H18NO3+]), 304 (13, [C19H13NO3+]), 166 (11). IR: ν̃ [cm−1] = 2968 (w), 2932 (w), 2903 (w), 2839 (w), 2201 (m), 1697 (s), 1605 (s), 1578 (s), 1522 (m), 1508 (s), 1441 (m), 1412 (s), 1379 (m), 1354 (m), 1339 (m), 1300 (m), 1280 (m), 1254 (s), 1227 (m), 1196 (m), 1175 (m), 1159 (m), 1132 (s), 1113 (m), 1094 (m), 1076 (m), 1045 (m), 1030 (m), 1007 (m), 982 (w), 966 (w), 947 (w), 925 (w), 899 (m), 862 (w), 842 (s), 826 (s), 799 (s), 770 (m), 640 (m). Anal. calcd. for C22H21NO3 (347.2): C 76.06, H 6.09, N 4.03; Found: C 75.82, H 6.64, N 3.85.

4.2.16. 7-(Diethylamino)-4-((1-tosyl-1H-indol-3-yl)ethynyl)-2H-chromen2-one (3p) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 5:1) compound 3p (174 mg, 87%) was obtained as a yellow solid, Mp 195 °C; Rf (n-hexane/ethyl acetate 5:1) = 0.07.1H NMR (600 MHz, CDCl3): δ 1.23 (t, J = 7.1 Hz, 6 H), 2.36 (s, 3 H), 3.44 (q, J = 7.1 Hz, 4 H), 6.27 (s, 1 H), 6.52 (d, J = 2.4 Hz, 1 H), 6.64–6.76 (m, 1 H), 7.26–7.29 (m, 2 H), 7.37 (td, J = 7.5, 1.1 Hz, 1 H), 7.42 (ddd, J = 8.4, 7.2, 1.3 Hz, 1 H), 7.69–7.76 (m, 2 H), 7.83 (d, J = 8.4 Hz, 2 H), 7.97 (s, 1 H), 8.01 (dt, J = 8.4, 0.9 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ 12.5 (CH3), 21.8 (CH3), 31.1 (Cquat), 45.3 (CH2), 88.1 (Cquat), 92.2 (Cquat), 98.0 (CH), 103.7 (Cquat), 109.3 (CH), 111.4 (CH), 113.9 (CH), 120.6 (CH), 124.3 (CH), 126.0 (CH), 127.2 (CH), 127.6 (CH), 130.3 (CH), 130.3 (Cquat), 130.8 (CH), 134.3 (Cquat), 134.8 (Cquat), 137.2 (Cquat), 145.9 (Cquat), 150.8 (Cquat), 156.3 (Cquat), 161.6 (Cquat). EI-MS (70 eV, m/z (%)): 511 (19), 510 (47, [M+]), 496 (19), 495 (59, [C29H23N2O4S+]), 356 (31), 355 (23, [C23H19N2O2+]), 342 (13), 341 (61, [C23H19NO2+]), 340 (100, [C22H16N2O2+]), 312 (13), 311 (11), 284 (12), 283 (23, [C19H9NO2+]), 91 (10, [C7H7+]). IR: ν̃ [cm−1] = 2965 (w), 2922 (w), 2901 (w), 2870 (w), 2210 (w), 1694 (s),

4.2.14. 7-(Diethylamino)-4-((4-(dimethylamino)phenyl)ethynyl)-2Hchromen-2-one (3n) According to GP after chromatography on silica gel (n-hexane/ethyl acetate 5:1) compound 3n (145 mg, 80%) was obtained as a yellow solid, Mp 176 °C; Rf (n-hexane/ethyl acetate 5:1) = 0.27. 1H NMR (600 MHz, CDCl3): δ 1.21 (t, J = 7.1 Hz, 6 H), 3.03 (s, 6 H), 3.42 (q, J = 7.1 Hz, 4 H), 6.18 (s, 1 H), 6.48 (d, J = 2.5 Hz, 1 H), 6.62 (d, J = 2.5 Hz, 1 H), 6.68 (d, J = 8.9 Hz, 2 H), 7.52–7.41 (m, 2 H), 7.72 (d, J = 8.9 Hz, 1 H). 13C NMR (151 MHz, CDCl3): δ 12.6 (CH3), 40.2 (CH3), 364

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1609 (s), 1578 (m), 1551 (m),1512 (m), 1493 (w), 1472 (w), 1447 (m), 1416 (s), 1377 (s), 1360 (m), 1341 (m), 1298 (w), 1283 (m), 1269 (m), 1231 (m), 1190 (m), 1175 (s), 1144 (m), 1223 (s), 1096 (s), 1082 (s), 1036 (m), 1011 (w), 986 (w), 955 (m), 935 (w), 928 (w), 901 (w), 858 (w), 839 (w), 822 (m), 800 (m), 791 (m), 746 (s), 702 (m), 687 (m), 660 (s), 646 (w), 615 (m). Anal. calcd. for C30H26N2O3S (510.2): C 70.57, H 5.13, N 5.49, S 6.28; Found: C 70.87, H 5.43, N 5.44, S 6.01.

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