Direct coupling of haloquinolines and sulfonyl chlorides leading to sulfonylated quinolines in water

Tetrahedron Letters 60 (2019) 214–218

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Tetrahedron Letters journal homepage: www.elsevier.com/locate/tetlet

Direct coupling of haloquinolines and sulfonyl chlorides leading to sulfonylated quinolines in water Pengli Bao a, Leilei Wang a, Qishun Liu a, Daoshan Yang a,c, Hua Wang a, Xiaohui Zhao b,⇑, Huilan Yue b, Wei Wei a,b,c,⇑ a

School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, Shandong, China Qinghai Provincial Key Laboratory of Tibetan Medicine Research and Key Laboratory of Tibetan Medicine Research, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Qinghai 810008, China c College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, PR China b

a r t i c l e

i n f o

Article history: Received 21 October 2018 Revised 5 December 2018 Accepted 7 December 2018 Available online 8 December 2018 Keywords: Haloquinolones Sulfonylated quinolines Zinc powder Sulfonyl chlorides In water

a b s t r a c t A simple and efficient method has been developed for construction of sulfonylated quinolines via coupling of haloquinolines and sulfonyl chlorides in water. The present methodology provides an attractive approach to various sulfonylated quinolines in moderate to good yields with favorable functional group tolerance, which has the advantages of operation simplicity, readily available starting materials, excellent regioselectivity, scale-up synthesis, and organic solvent-free conditions. Ó 2018 Elsevier Ltd. All rights reserved.

As one of the most important N-heterocycle structural motifs, quinolines are widely existed in numerous natural products, bioactive compounds, and advanced functional materials [1]. Consequently, the construction of valuable functionalized quinoline derivatives in chemo- and regioselective fashion is a prominent research topic in synthetic and pharmaceutical chemistry [2]. Sulfone group represents a class of highly valuable organic functionality, which is often introduced into organic frameworks to enhance the possible biological activities during the drug design [3]. In particular, sulfonated quinolines have drawn increasing attention from chemists owing to their important biological activity and pharmacological value [4]. Generally, sulfonated quinolines are prepared by the coupling of 2-haloquinoliness with sulfonate [5] and the thioetherification of haloquinolines with thiols and subsequent oxidation [6]. Alternative methods for the sulfonylation of quinoline N-oxides with sodium sulfonates [7] and sulfonyl hydrazides [8] have also been developed. These methods, although effective, require relatively harsh reaction conditions or tedious ⇑ Corresponding authors at: School of Chemistry and Chemical Engineering, Qufu Normal University, Qufu 273165, Shandong, China (W. Wei). Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810008, Qinghai, China (X. Zhao). E-mail addresses: [email protected] (X. Zhao), [email protected] (W. Wei). https://doi.org/10.1016/j.tetlet.2018.12.016 0040-4039/Ó 2018 Elsevier Ltd. All rights reserved.

operation procedures. In addition, the sulfonating reagents such as sodium sulfinates and sulfonyl hydrazides have limited commercial availability, which are usually synthesized from the corresponding sulfonyl chlorides in the presence of sulfinate salts [9] or dangerous hydrazine hydrate under alkaline condition [10]. Recently, the sulfonylation of quinoline N-oxides with sulfonyl chlorides have been reported. In 2013, Cui’s group developed an elegant copper-catalyzed protocol for synthesis of 2-sulfonylquinolinesthe via sulfonylation of quinoline N-oxides with sulfonyl chlorides and subsequent reduction [11]. In 2015, Zhao et al. also presented the H-phosphonate-mediated sulfonylation of quinoline N-oxides with sulfonyl chlorides leading to 2-sulfonyl quinolines [12]. Recently, He and co-workers report an ultrasound accelerated one-pot synthesis of 2-sulfonylquinolines from quinoline N-oxides with sulfonyl chlorides [13]. Nevertheless, the methods for sulfonylation of quinoline N-oxides encountered certain drawback of low regioselectivity. In contrast, the direct sulfonylation of halogenated quinolines has an advantage of the completely controllable regioselectivity. Therefore, the development of mild, convenient and efficient method for regioselective synthesis of sulfonylated quinolines from haloquinolines and sulfonyl chlorides is highly desirable. Water is an attractive green solvent for numerous organic reactions owing to its low cost, natural abundance and eco-friendly

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P. Bao et al. / Tetrahedron Letters 60 (2019) 214–218 Table 1 Optimization of reaction conditions.a

a b c

Entry

Reductant (equiv.)

2a

Conditions

Yield (%)b

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

Fe powder(1.5) Al powder (1.5) Mg powder (1.5) Mn powder (1.5) Zn powder (1.5) Zn powder (1) Zn powder (0.75) Zn powder (1) Zn powder (1) Zn powder (1) Zn powder (1) Zn powder (1) –

2 (equiv.) 2 (equiv.) 2 (equiv.) 2 (equiv.) 2 (equiv.) 2 (equiv.) 2 (equiv.) 1.5(equiv.) 2 (equiv.) 2 (equiv.) 2 (equiv.) 2 (equiv.) 2 (equiv.)

100 °C, 12 h 100 °C, 12 h 100 °C, 12 h 100 °C, 12 h 100 °C, 12 h 100 °C, 12 h 100 °C, 12 h 100 °C, 12 h 80 °C, 12 h 60 °C, 12 h r.t., 24 h ultrasonic radiation, 1 h 80 °C, 12 h

85 N.R. N.R. 78 82 91 84 82 93(89%) 76 20% 13%c 0

Reaction conditions: 1a (0.3 mmol), 2a, reductant, 60–100 °C, water (1.5 mL). NMR yields based on 1a; isolated yield in bracket. Ultrasonic radiation: 28KHz, 40 W.

properties [14]. However, to the best of our knowledge, there is no example of the sulfonylation of haloquinolines with sulfonyl chlorides in water was reported. As part of our ongoing interest in the construction of sulfone-containing compounds [15] and green organic synthesis [16], herein, we wish to report a simple and convenient method for the construction of sulfonylated quinolines from inexpensive and readily available haloquinolines and sulfonyl chlorides in water (Scheme 1). In our initial investigation, the reaction of 2-chloroquinoline (1a) with tosyl chloride (2a) was conducted in the presence of iron powder (1.5 equiv.) in water at 100 °C for 12 h, and a 85% yield (determined by 1H NMR) of 2a was observed (Table 1, entry 1). Encouraged by this promising result, various reaction parameters were screened to optimize the reaction conditions. A series of cheap metal powders were investigated and zinc powder was found to be the best choice for this reaction (Table 1, entries 2– 5). Next, other reaction parameters such as equivalents of 2a, loading of reductant and reaction temperature were examined (Table 1, entries 6–10). The reaction efficiency was obviously improved by decreasing the amount of zinc powder to 1. quiv (Table 1, entry 6). However, further reduction of zinc powder to 0.75 equiv. resulted in a lower yield (Table 1, entry 7). Adjusting the loading of 2a to 1.5 equiv. gave a relatively lower yield of the product 3a (Table 1, entry 8). The decrease of the temperature found that the reaction at 80 °C gave the best result (Table 1, entries 6, 9– 11). Performing the reaction under ultrasonic radiation gave 3a in only 13% yield (Table 1, entry 12). No reaction occurred in the

Scheme 1. Synthetic route to sulfonylated quinolines.

absence of zinc powder, and the raw material 1a was completely recovered (Table 1, entry 13). With the optimized reaction conditions in hand, the substrate scope ing 2-sulfonylquinoline 3cof sulfonyl chlorides was first evaluated (Table 2). Aryl sulfonyl chlorides with a series of important functional-groups (i.e., -Me, -OMe, -F, -Cl, -Br, -NO2, -CN and CF3) on benzene ring were well tolerated to produce the desired 2sulfonylquinolines in good to high yields (Table 2, 3a–3k). Sterically hindered 2-methylbenzenesulfonylchloride survived well to give the correspond in good yield. Regardless of their electronic characters, 2-chloroquinoline coupled efficiently with aryl sulfonyl chlorides to deliver the sulfonylated products in good to excellent yields (3d–3k). Notably, the reaction of 2-chloroquinoline with naphthalene-2-sulfonyl chloride and heterocycle sulfonyl chloride such as 2-thiophenesulfonyl chloride afforded the desired products (3l and 3m) in 85% and 81% yields, respectively. It should be noted that this reaction was also extended to aliphatic sulfonyl chlorides such as benzylsulfochloride, n-propanesulfonyl chloride and cyclopropylsulfonyl chloride (3n–3p). Encouraged by these results, we subsequently turned to haloquinoline substrates. Delightfully, both substituted 2-chloroquinolines and 4-chloroquinolines reacted efficiently with tosyl chloride affording the desired products (3q– 3x) in good to excellent yields. Moreover, 2-bromoquinoline and 2-iodoquinoline are also suitable substrates, providing the desired product 3a in good yields. In addition, 1-chloroisoquinoline could also used in this reaction to produce the sulfonylated product 3y in 68% yield. Notably, 4-chloro-2-tosylquinoline 3z [13] was selectively obtained in 70% yield when the reaction of 2,4-dichloroquinoline and tosyl chloride was carried out under standard conditions. To verify the practicality of the present coupling reaction, a gram scale reaction was conducted under the optimized reaction conditions. Delightfully, the present reaction provided the 2tosylquinoline 3a in 85% yield (1.20 g), showing an excellent potential application for gram scale synthesis (Scheme 2). To understand the reaction mechanism of this coupling reaction, some control experiments were conducted. No reaction occurred between 1a and thiosulfonate (4a) under optimal reaction conditions, ruling out the possibility of thiosulfonate involving

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P. Bao et al. / Tetrahedron Letters 60 (2019) 214–218 Table 2 Substrate scope.a,b

a

Reaction conditions: 1 (0.3 mmol), 2 (0.6 mmol), Zn powder (0.3 mmol), water (1.5 mL), 80 °C, 12 h. Isolated yields based on 1.

b

Scheme 2. Gram-scale synthesis.

in this reaction system (Scheme 3(a)). Using zinc(II) p-toluenesulfonate (5a) instead of tosyl chloride resulted in the total recovery of the starting material 1a, suggesting that 5a might not be the possible reaction intermediate (Scheme 3(b)). Treatment of 1a with zinc bis-sulphinate (6a) in water at 80 °C for 12 h, a 90% NMR yield of 3a was obtained. This observation indicated that 6a

P. Bao et al. / Tetrahedron Letters 60 (2019) 214–218

217

Scheme 3. Control experiments.

Scheme 4. Possible reaction pathway.

is the active intermediate of this coupling reaction (Scheme 3(c)) and the present reaction may proceed via a SNAr reaction. On the basis of the above experimental results and relevant reports [11–13,17], a possible reaction mechanism is proposed in Scheme 4. The sulfonyl chloride 2 is first reduced by zinc powder to generate a zinc bis-sulphinate intermediate I. Then, intermediate I reacted with 2-chloroquinoline 1 to produce the desired sulfonylated quinoline 3 via SNAr reaction pathway along with the release of the zinc chloride. In summary, a novel and efficient protocol was developed for the one-pot construction of various sulfonylquinolines through zinc powder mediated coupling reaction of haloquinolines with sulfonyl chlorides in water under base and extra activator-free condition. In this reaction, the in situ generated zinc bis-sulphinate compounds play dual roles: sulfone reagent and activator. The present methodology provide a practical protocol to construct various 2-sulfonylquinolines.

[2]

[3]

Acknowledgements This work was supported by the International Cooperation Project of Qinghai Province (2018-HZ-806), Qinghai key laboratory of Tibetan medicine research (2017-ZJ-Y11), Natural Science Foundation of Shandong Province (ZR2018MB009 and ZR2016JL012), and the National Natural Science Foundation of China (No. 21302109 and 21302110). Appendix A. Supplementary data

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