Palladium-catalyzed four-component carbonylation of allenes, alcohols and nitroarenes

Journal of Catalysis 381 (2020) 271–274

Contents lists available at ScienceDirect

Journal of Catalysis journal homepage: www.elsevier.com/locate/jcat

Priority Communication

Palladium-catalyzed four-component carbonylation of allenes, alcohols and nitroarenes Hui-Qing Geng a, Chen-Yang Hou a, Le-Cheng Wang a, Jin-Bao Peng a, Xiao-Feng Wu a,b,⇑ a b

Department of Chemistry, Zhejiang Sci-Tech University, Xiasha Campus, Hangzhou 310018, People’s Republic of China Leibniz-Institut für Katalyse e. V. an der Universität Rostock, Albert-Einstein-Strabe 29a, Rostock 18059, Germany

a r t i c l e

i n f o

Article history: Received 2 October 2019 Revised 6 November 2019 Accepted 7 November 2019

Keywords: Carbonylation Palladium catalyst Nitroarenes Allenes b-lactams Multi-component reaction

a b s t r a c t In this communication, a highly selective palladium-catalyzed carbonylative four components procedure for the transformation of allenes, alcohols and nitroarenes has been developed. The desired 2aminomethyl substituted 3-arylacrylates were produced in good yields with Mo(CO)6 as the solid CO source. Furthermore, nitroarenes have been used as reaction partners and oxidant in this catalytic system. Additionally, further synthetic application of our obtained products has been realized as well and a-alkylidene b-lactams were prepared. Ó 2019 Elsevier Inc. All rights reserved.

Allene is a class of potent chemicals with exceptional chemical reactivities due to the presence of the 1,2-diene moiety [1]. Numerous synthetic procedures have been established for the fast preparation of sophisticated molecules with allenes as one of the starting substrates. On the other hand, carbonylation reactions have already been recognized as a powerful methodology for the synthesis of carbonyl-containing compounds while it can also increase the carbon chain in the meantime [2]. Not surprisingly, various novel allene based carbonylative transformations have been developed during the past years [3–5]. For example, the research group of Bäckvall have developed a series of elegant protocols for carbocyclization-carbonylation of allenynes and analogues [4]. In 2015, Ding, Wang and their co-workers reported an novel palladium-catalyzed carbonylation of allenes with amines and alcohol [5]. With their own developed aromatic spiroketalbased diphosphine (SKP) as the chiral ligand and using Cu(II) salt as the oxidant, a wide range of a-methylene-b-arylamino acid esters were produced in good yields with excellent enantioselectivity and high regioselectivity (Scheme 1, eq a). Inspired by this achievement and also our own experiences on carbonylation chemistry, we become interested to develop a new procedure with

⇑ Corresponding author at: Department of Chemistry, Zhejiang Sci-Tech University, Xiasha Campus, Hangzhou 310018, People’s Republic of China. E-mail address: [email protected] (X.-F. Wu). https://doi.org/10.1016/j.jcat.2019.11.009 0021-9517/Ó 2019 Elsevier Inc. All rights reserved.

different selectivity which could obtain 2-aminomethyl substituted 3-arylacrylates as the terminal products (Scheme 1, eq b) [6]. To establish the catalytic system, we selected commercially available phenylallene and 4-nitrotoluene as the model substrates and using methanol as the fourth reaction partner and also as the solvent. With Mo(CO)6 as the CO source and DiPEA (N,Ndiisopropylethylamine) as the base, catalyzed by Pd(OAc)2/BINAP at 100 °C in methanol, the desired methyl (Z)-3-phenyl-2-((ptolylamino)methyl)acrylate (P1) was formed in 32% yield (Table 1, entry 1). By replacing the base with NEt3, the yield of P1 decreased to 25% (Table 1, entry 2); and only traces amount of the target product could be detected when using K2CO3 as the base (Table 1, entry 3). Subsequently, the effects from phosphine ligands were checked. In our tested ligands, monophosphine ligands and bidentate ligands with large bite angle all lead to low reaction efficiency (Table 1, entries 4–7). The reaction works much better with phosphine ligands which have a bite angle between 80–100° (Table 1, entries 8–14) [7]. Here DPPM might act as monophosphine ligand rather than chelating phosphine ligand. To our surprise, the reaction outcome was slightly improved by decreasing the loading of palladium catalyst to 5 mol % (Table 1, entry 15). Delightly, 80% isolated yield of the target product can be achieved with 2.5 mol % of Pd(OAc)2 and 3 mol % of DPPBz (Table 1, entry 16). Moreover, it is also worthy to mention that palladium precursors, loading of DiPEA and Mo(CO)6, reaction temperature and reaction concentration were all varied, but can not further improve the yield of the

272

H.-Q. Geng et al. / Journal of Catalysis 381 (2020) 271–274

Scheme 1. Palladium-catalyzed four components carbonylative transformation of allenes.

Table 1 Optimization of reaction conditions.a Entry

Ligand

Bite angle

Base

Yield (%)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

BINAP BINAP BINAP PPh3 BuPAd2 Xantphos DPPPe DPEphos DPPF DPPB DPPP DPPE DPPM DPPBz DPPBz DPPBz DPPBz

93 93 93 / / 108

DiPEA NEt3 K2CO3 DiPEA DiPEA DiPEA DiPEA DiPEA DiPEA DiPEA DiPEA DiPEA DiPEA DiPEA DiPEA DiPEA DiPEA

32 25 <1 <1 <1 <1 <1 11 24 50 46 24 <1 53 59b 80c 63d

104 99 94 91 86 73 83 83 83 83

a Reaction condition: MeOH (1 mL), phenylallene (0.5 mmol), 4-nitrotoluene (1.5 mmol), Pd(OAc)2 (10 mol %), ligand (bidentate ligand = 12 mol %; monophosphine ligand = 24 mol %), Mo(CO)6 (0.5 mmol), base (2 mmol), 100 °C, 12 h, yields determined by GC analysis using dodecane as internal standard. b Pd(OAc)2 (5 mol %), DPPBz (6 mol %). c Pd(OAc)2 (2.5 mol %), DPPBz (3 mol %), isolated yield. d Pd(OAc)2 (1 mol %), DPPBz (1.2 mol %). BINAP : (2,20 -bis(diphenylphosphino)1,10 -binaphthyl). DPPPe: 1,5-bis(diphenylphosphino)pentane. DPPBz: 1,2-bis (diphenylphosphino)benzene.

target product. Notably, compared with the selectivity obtained by Ding, Wang and their co-workers [5], the results obtained here is can be explained by two reasons: (1) the effect from ligand applied which forms different key intermediate; (2) terminal selectivity is favored in palladium-catalyzed transformation of allenes [1]. After having established the catalytic system, we immediately tested the substrate scope and limitation of this procedure. Under our standard conditions, various nitro compounds were tested at the first stage (Scheme 2). Moderate to excellent yields of the target products can be obtained in general. Aromatic nitro compounds with alkyl substituents can be transformed effectively and provide the corresponding products in 72–81% yields (P1–P3). Furthermore, functional groups including ether, thioether, trifluoromethyl, halogen, and ketone can all be well tolerated and give the target compounds in good yields (P4–P13). However, moderate yield was obtained in case para-alkene substituted nitrobenzene was applied (P8). Due to the alkene group can be easily oxidized in the presence of palladium catalyst under oxidative condition. Additionally, 8-nitroquinoline and 5-nitroquinoline can be used as the substrates as well (P14, P15). The reason for the low yield with 8-nitroquinoline is due to the chelating effect from the two nitrogen atom which inhibited the reactivity of palladium catalyst (P14). It is also important to mention that aliphatic nitro compounds failed in this reaction system, no target chemical could

Scheme 2. Synthesis of 2-aminomethyl substituted 3-arylacrylates from nitroarenes and allenes. Reaction condition: MeOH (1 mL), allene (0.5 mmol), nitroarene (1.5 mmol), Pd(OAc)2 (2.5 mol %), DPPBz (3 mol %), Mo(CO)6 (0.5 mmol), DiPEA (2 mmol), 100 °C, 12 h, isolated yields.

be detected. For the next step, different allenes were tested under the identical conditions. Numbers of aromatic substituted allenes were prepared and tested [8], as expected, good yields of the target

H.-Q. Geng et al. / Journal of Catalysis 381 (2020) 271–274

273

Scheme 4. Proposed reaction mechanism.

Scheme 3. Synthesis of 2-aminomethyl substituted 3-arylacrylates from alcohols. Reaction condition A: Phenylallene (0.5 mmol), 4-nitrotoluene (1.5 mmol), Pd (OAc)2 (2.5 mol %), DPPBz (3 mol %), Mo(CO)6 (0.5 mmol), DiPEA (2 mmol), ROH (1 mL), 100 °C, 12 h, isolated yields. Reaction condition B: ROH (5 equiv), phenylallene (0.5 mmol), 4-nitrotoluene (1.5 mmol), Pd(OAc)2 (10 mol %), DPPBz (12 mol %), Mo(CO)6 (0.5 mmol), DiPEA (2 mmol), THF:tBuOH (1:4, 1 mL), 100 °C, 12 h, isolated yields.

compounds were produced successfully (P16–P21). a-Methyl- and a-phenyl-substituted phenylallenes are suitable substrates as well, good yields of the corresponding products can be isolated (P22, P23). Remarkably, besides aromatic allenes, aliphatic allene is shown to be suitable starting material as well and 67% of the corresponding product can be obtained (P24). Finally, alcohols were tested with phenylallene and 4nitrotoluene as the reaction partners (Scheme 3). Instead of using

alcohol as the solvent, we can decrease the loading of alcohol to 5 equiv and using THF:tBuOH (1:4) as the reaction media. Although lower yield was obtained (For P1, 80% vs 62%), these new conditions offer a possibility to extend alcohols from low boiling substrates to solid alcohols. As we shown, besides ethanol, propanol, butanol, pentanol, and cyclohexanemethanol, heavy alcohols such as benzylic alcohols and 2-phenyl ethanol can be all be transformed into the corresponding 3-arylacrylates in good yields. A possible reaction pathway is been proposed based on our results (Scheme 4). The first step, an active Pd(II) complex A will be formed in the presence of ligand and alcohol. Subsequently, CO inserts into the RO-Pd bond via coordination with free CO or ligand exchange with Mo(CO)6 to give the key palladium intermediate B. Then, the CO inserted palladium complex B reacted with allene and followed by nucleophilic attack of aniline to give the final products [6,9]. Meanwhile the released Pd(0) complex will be regenerated under the assistant of nitro compounds and alcohol and get ready for the next catalytic cycle. Finally, synthetic application of our obtained products was performed as well (Scheme 5). By using a literature known procedure [10], our products were transformed into the corresponding aalkylidene b-lactams in good yields. In summary, a palladium-catalyzed four-component methodology for the selective synthesis of 2-aminomethyl substituted 3arylacrylates has been developed. With readily available allenes, nitroarenes and alcohols as the substrates, moderate to excellent yields of the desired esters can be isolated. In this catalytic system, Mo(CO)6 has been used as a stable solid CO surrogates with nitroarenes as both reaction partner and oxidant. Additionally, further synthetic application of our obtained products has been realized as well.

Scheme 5. Synthesis of a-alkylidene b-lactams.

274

H.-Q. Geng et al. / Journal of Catalysis 381 (2020) 271–274

Funding sources The authors thank the financial supports from National Natural Science Foundation of China (21772177, 21801225). Notes There are no conflicts to declare. General procedure A 15 mL sealed tube containing phenylallene (0.5 mmol) and 4nitrotoluene (1.5 mmol, 3 equiv), Pd(OAc)2 (2.5 mol%), DPPBz (3 mol%), Mo(CO)6 (0.5 mmol, 1 equiv) and was evacuated and purged with nitrogen gas three times. Then, methanol (1 mL) and DiPEA (2 mmol, 4 equiv) was added to the reaction tube by syringe. The tube was sealed and the mixture was stirred at 100 °C for 12 h. After the reaction was completed, the reaction mixture was filtered and concentrated under vacuum. The crude product was purified by column chromatography on silica gel to afford the corresponding product. Appendix A. Supplementary material Supplementary data to this article can be found online at https://doi.org/10.1016/j.jcat.2019.11.009. References [1] (a) N. Krause, A.S.K. Hashmi (Eds.), Modern Allene Chemistry, Wiley-VCH, Weinheim, Germany, 2004; (b) S. Yu, S. Ma, Allenes in catalytic asymmetric synthesis and natural product syntheses, Angew. Chem. Int. Ed. 51 (2012) 3074–3112; (c) R. Zimmer, C.U. Dinesh, E. Nandanan, F.A. Khan, Palladium-catalyzed reactions of allenes, Chem. Rev. 100 (2000) 3067–3126; (d) T. Lechel, F. Pfrengle, H.U. Reissig, R. Zimmer, Three carbons for complexity! recent developments of palladium-catalyzed reactions of allenes, ChemCatChem 5 (2013) 2100–2130; (e) B. Yang, Y. Qiu, J.E. Bäckvall, Control of selectivity in palladium(II)catalyzed oxidative transformations of allenes, Acc. Chem. Res. 51 (2018) 1520–1531. [2] (a) For selected reviews on carbonylation published since 2019, see: J.-B. Peng, F.-P. Wu, X.-F. Wu, First-row transition-metal-catalyzed carbonylative transformations of carbon electrophiles Chem. Rev. 119 (2019) 2090–2127; (b) J.-B. Peng, H.-Q. Geng, X.-F. Wu, The chemistry of CO: carbonylation, Chem 5 (2019) 526–552; (c) K. Ma, B.S. Martin, X. Yin, M. Dai, Natural product syntheses via carbonylative cyclizations, Nat. Prod. Rep. 36 (2019) 174–219; (d) R. Mancuso, N. Della Ca’, L. Veltri, I. Ziccarelli, B. Gabriele, PdI2-based catalysis for carbonylation reactions: a personal account, Catalysts 9 (2019) 610–642; (e) S. Zhao, N.P. Mankad, Metal-catalysed radical carbonylation reactions, Catal. Sci. Technol. 9 (2019) 3603–3613. [3] (a) For selected recent examples on allenes carbonylation see: D.-Y. Zhou, E. Yoneda, K. Onitsuka, S. Takahashi, Ruthenium-catalyzed carbonylation of allene: direct synthesis of methacrylates and methacrylamides Chem. Commun. (2002) 2868–2869; (b) M. Kajitani, I. Kamiya, A. Nomoto, N. Kihara, A. Ogawa, Transition-metalcatalyzed carbonylation of allenes with carbon monoxide and thiols, Tetrahedron 62 (2006) 6355–6360.

[4] (a) C.M.R. Volla, J. Mazuela, J.E. Bäckvall, Palladium-catalyzed oxidative carbocyclization-carbonylation of allenynes and enallenes, Chem. Eur. J. 20 (2014) 7608–7612; (b) C.M.R. Volla, J.-E. Bäckvall, Palladium-catalyzed oxidative domino carbocyclization-carbonylation-alkynylation of enallenes, Org. Lett. 16 (2014) 4174–4177; (c) C. Zhu, B. Yang, J.-E. Bäckvall, Highly selective cascade C-C bond formation via palladium-catalyzed oxidative carbonylation-carbocyclizationcarbonylation-alkynylation of enallenes, J. Am. Chem. Soc. 137 (2015) 11868–11871; (d) Y. Qiu, B. Yang, C. Zhu, J.-E. Bäckvall, Highly efficient cascade reaction for selective formation of spirocyclobutenes from dienallenes via palladiumcatalyzed oxidative double carbocyclization-carbonylation-alkynylation, J. Am. Chem. Soc. 138 (2016) 13846–13849; (e) C. Zhu, B. Yang, Y. Qiu, J.-E. Bäckvall, Highly selective construction of sevenmembered carbocycles by olefin-assisted palladium-catalyzed oxidative carbocyclization-alkoxycarbonylation of bisallenes, Angew. Chem. Int. Ed. 55 (2016) 14405–14408; (f) Y. Qiu, B. Yang, T. Jiang, C. Zhu, J.-E. Bäckvall, Palladium-catalyzed oxidative cascade carbonylative spirolactonization of enallenols, Angew. Chem. Int. Ed. 56 (2017) 3221–3225; (g) B. Yang, Y. Qiu, T. Jiang, W.D. Wulff, X. Yin, C. Zhu, J.-E. Bäckvall, Enantioselective palladium-catalyzed carbonylative carbocyclization of enallenes via cross-dehydrogenative coupling with terminal alkynes: efficient construction of a-chirality of ketones, Angew. Chem. Int. Ed. 56 (2017) 4535–4539. [5] J. Liu, Z. Han, X. Wang, Z. Wang, K. Ding, Highly regio- and enantioselective alkoxycarbonylative amination of terminal allenes catalyzed by a spiroketalbased diphosphine/Pd(II) complex, J. Am. Chem. Soc. 137 (2015) 15346–15349. [6] (a) J.-B. Peng, H.-Q. Geng, F.-P. Wu, D. Li, X.-F. Wu, Selectivity controllable divergent synthesis of a, b-unsaturated amides and maleimides from alkynes and nitroarenes via palladium-catalyzed carbonylation, J. Catal. 375 (2019) 519–523; (b) H.-Q. Geng, J.-B. Peng, X.-F. Wu, Palladium-catalyzed oxidative carbonylative coupling of arylallenes, arylboronic acids and nitroarenes, Org. Lett. 21 (2019) 8215–8218. [7] M.-N. Birkholz (née Gensow), Z. Freixa, P.W.N.M. van Leeuwen, Bite angle Effects of diphosphines in C-C and C-X bond forming cross coupling, Reactions Chem. Soc. Rev. 38 (2009) 1099–1118. [8] (a) H. Clavier, K. Le Jeune, I. de Riggi, A. Tenaglia, G. Buono, Highly selective cobalt-mediated [6 + 2] cycloaddition of cycloheptatriene and allenes, Org. Lett. 13 (2011) 308–311; (b) J. Kuang, S. Ma, An efficient synthesis of terminal allenes from terminal 1alkynes, J. Org. Chem. 74 (2009) 1763–1765. [9] (a) L. He, M. Sharif, H. Neumann, M. Beller, X.-F. Wu, A convenient palladiumcatalyzed carbonylative synthesis of 4(3H)-quinazolinones from 2bromoformanilides and organo nitros with Mo(CO)6 as a multiple promoter, Green Chem. 16 (2014) 3763–3767; (b) F. Zhou, D.-S. Wang, T.G. Driver, Palladium-catalyzed formation of Nheteroarenes from nitroarenes using molybdenum hexacarbonyl as the source of carbon monoxide, Adv. Synth. Catal. 357 (2015) 3463–3468; (c) N. Jana, F. Zhou, T.G. Driver, Promoting reductive tandem reactions of Nitrostyrenes with Mo(CO)6 and a palladium catalyst to produce 3H-indoles, J. Am. Chem. Soc. 137 (2015) 6738–6741; (d) J.D. Gargulak, W.L. Gladfelter, Homogeneous catalytic carbonylation of nitroaromatics. 6. Synthesis and structure of two bis(carbamoyl) complexes of ruthenium, Inorg. Chem. 33 (1994) 253–257; (e) F. Ragaini, M. Gasperini, S. Cenini, L. Arnera, A. Caselli, P. Macchi, N. Casati, Mechanistic study of the palladium-phenanthroline catalyzed carbonylation of nitroarenes and amines: palladium-carbonyl intermediates and bifunctional effects, Chem. Eur. J. 15 (2009) 8064–8077; (f) E. Gallo, F. Ragaini, S. Cenini, F. Demartin, Investigation of the reactivity of palladium(0) complexes with nitroso compounds: relevance to the palladium phenanthroline-catalysed carbonylation reactions of nitroarenes, J. Organomet. Chem. 586 (1999) 190–195. [10] J. Xia, Y. Nie, G. Yang, Y. Liu, I.D. Gridnev, W. Zhang, Ir-catalyzed asymmetric hydrogenation of a-alkylidene b-lactams and cyclobutanones, Chin. J. Chem. 36 (2018) 612–618.