Electrocatalytic Synthesis of gem-Bisarylthio Enamines and α-Phenylthio Ketones via a Radical Process under Mild Conditions

Abstract

The novel method for the synthesis of gem-bisarylthio enamines and α-phenylthio ketones was developed via the coupling of α-substituted vinyl azides with thiols in the presence of tetrabutylammonium iodide (TBAI) as a redox catalyst and electrolyte at room temperature. Electronic properties were crucial in the generated products. This protocol features metal- and oxidant-free materials, broad tolerance of substrates, and mild reaction conditions.

Key words

electrocatalytic - vinyl azides - thiophenols - gem-bisarylthio enamines - metal-free

Publication History

Received: 16 October 2020

Accepted after revision: 11 December 2020

Accepted Manuscript online:
11 December 2020

Article published online:
08 March 2021

• References and Notes

• 1a Zhang X, Liu C, Deng Y, Cao S. Org. Biomol. Chem. 2020; 18: 7540
• 1b Fujita T, Fuchibe K, Ichikawa J. Angew. Chem. Int. Ed. 2019; 58: 390
• 1c Zhang X, Cao S. Tetrahedron Lett. 2017; 58: 375
• 1d Chelucci G. Chem. Rev. 2012; 112: 1344
• 1e Hu J, Han X, Yuan Y, Shi Z. Angew. Chem. Int. Ed. 2017; 56: 13342
• 1f Hu J, Zhao Y, Shi Z. Nat. Catal. 2018; 1: 860
• 1g Yoo W.-J, Kondo J, Rodríguez-Santamaría JA, Nguyen TV. Q, Kobayashi S. Angew. Chem. Int. Ed. 2019; 58: 6772
• 1h Guo Y.-Q, Wang R, Song H, Liu Y, Wang Q. Org. Lett. 2020; 22: 709
• 2 Yao C, Wang S, Norton J, Hammond M. J. Am. Chem. Soc. 2020; 142: 4793
• 3 Uetake Y, Isoda M, Niwa T, Hosoya T. Org. Lett. 2019; 21: 4933
• 4 Gao Y, Wu Z.-Q, Engle KM. Org. Lett. 2020; 22: 5235
• 5 Davis FA, Mancinelli PA. J. Org. Chem. 1980; 45: 2597
• 6 Ni J, Mao X, Zhang A. Adv. Synth. Catal. 2019; 9: 2004
• 7a Fu J, Zanoni G, Anderson EA, Bi X. Chem. Soc. Rev. 2017; 46: 7208
• 7b Hayashi H, Kaga A, Chiba S. J. Org. Chem. 2017; 82: 11981
• 7c Hu B, DiMagno SG. Org. Biomol. Chem. 2015; 13: 3844
• 7d Jung N, Bräse S. Angew. Chem. Int. Ed. 2012; 51: 12169
• 8a Zhang B, Studer A. Chem. Soc. Rev. 2015; 44: 3505
• 8b Wang Y.-F, Toh KK, Ng EP. J, Chiba S. J. Am. Chem. Soc. 2011; 133: 6411
• 8c Ning Y, Ji Q, Liao P, Anderson EA, Bi X. Angew. Chem. Int. Ed. 2017; 56: 13805
• 8d Wang Y.-F, Lonca GH, Chiba S. Angew. Chem. Int. Ed. 2014; 53: 1067
• 8e Shu W, Lorente A, Gómez-Bengoa E, Nevado C. Nat. Commun. 2017; 8: 13832
• 8f Ning Y, Zhao X.-F, Wu Y.-B, Bi X. Org. Lett. 2017; 19: 6240
• 8g Wu S.-W, Liu F. Org. Lett. 2016; 18: 3642
• 8h Sun X, Yu S. Chem. Commun. 2016; 52: 10898
• 9a Chen W, Hu M, Wu J, Zou H, Yu Y. Org. Lett. 2010; 12: 3863
• 9b Reddy NN. K, Rao SN, Ravi C, Adimurthy S. ACS Omega 2017; 2: 5235
• 10a Gaydou M, Echavarren AM. Angew. Chem. Int. Ed. 2013; 52: 13468
• 10b Zhang F.-L, Wang Y.-F, Lonca GH, Zhu X, Chiba S. Angew. Chem. Int. Ed. 2014; 53: 4390
• 10c Qin C, Su Y, Shen T, Shi X, Jiao N. Angew. Chem. Int. Ed. 2016; 55: 350
• 10d Hassner A, Levy AB. J. Am. Chem. Soc. 1971; 93: 5469
• 10e Dey R, Banerjee P. Org. Lett. 2017; 19: 304
• 10f Wang Y.-F, Hu M, Hayashi H, Xing B, Chiba S. Org. Lett. 2016; 18: 99
• 10g Zhang F.-L, Zhu X, Chiba S. Org. Lett. 2015; 17: 3138
• 10h Lonca GH, Tejo C, Chan HL, Chiba S, Gagosz F. Chem. Commun. 2017; 53: 736
• 10i Zhu X, Chiba S. Chem. Commun. 2016; 52: 2473
• 11a Padwa A, Rasmussen JK, Tremper A. J. Am. Chem. Soc. 1976; 98: 2605
• 11b Xu H.-D, Zhou H, Pan Y.-P, Ren X.-T, Wu H, Han M, Han R.-Z, Shen M.-H. Angew. Chem. Int. Ed. 2016; 55: 2540
• 11c Zhu Z, Tang X, Li J, Li X, Wu W, Deng G, Jiang H. Org. Lett. 2017; 19: 1370
• 11d Tejeda JE. C, Irwin LC, Kerr MA. Org. Lett. 2016; 18: 4738
• 11e Siyang HX, Ji XY, Wu XR, Wu XY, Liu PN. Org. Lett. 2016; 18: 2323
• 11f Xiang L, Niu Y, Pang X, Yang X, Yan R. Chem. Commun. 2015; 51: 6598
• 11g Zhu Z, Tang X, Li X, Wu W, Deng G, Jiang H. J. Org. Chem. 2016; 81: 1401
• 11h Hu B, DiMagno SG. Org. Biomol. Chem. 2015; 13: 3844
• 12a Zhang F.-L, Wang Y.-F, Lonca GH, Zhu X, Chiba S. Angew. Chem. Int. Ed. 2014; 53: 4390
• 12b Katori T, Itoh S, Sato M, Yamataka H. J. Am. Chem. Soc. 2010; 132: 3413
• 12c Hassner A, Ferdinand ES, Isbister RJ. J. Am. Chem. Soc. 1970; 92: 1672
• 12d Dey R, Banerjee P. Org. Lett. 2017; 19: 304
• 12e Zhang Z, Kumar RK, Li G, Wu D, Bi X. Org. Lett. 2015; 17: 6190
• 13a Meldal M, Tornøe CW. Chem. Rev. 2008; 108: 2952
• 13b Bräse S, Gil C, Knepper K, Zimmermann V. Angew. Chem. Int. Ed. 2005; 44: 5188
• 13c Kolb HC, Finn MG, Sharpless KB. Angew. Chem. Int. Ed. 2001; 40: 2004
• 14 Ning Y, Mekareeya A, Babu KR, Anderson EA, Bi X. ACS Catal. 2019; 9: 4203
• 15a Qin H.-T, Wu S.-W, Liu J.-L, Liu F. Chem. Commun. 2017; 53: 1696
• 15b Chen W, Liu X, Chen E, Chen B, Shao J, Yu Y. Org. Chem. Front. 2017; 4: 1162
• 16a Ning Y, Zhao X.-F, Wu Y.-B, Bi X. Org. Lett. 2017; 19: 6240
• 16b Wang X, Li H, Qiu G, Wu J. Chem. Commun. 2019; 55: 2062
• 17a Wang Y.-F, Chiba S. J. Am. Chem. Soc. 2009; 131: 12570
• 17b Wang Y.-F, Toh KK, Ng EP. J, Chiba S. J. Am. Chem. Soc. 2011; 133: 6411
• 17c Lei W.-L, Feng K.-W, Wang T, Wu L.-Z, Liu Q. Org. Lett. 2018; 20: 7220
• 17d Mao L.-L, Zheng D.-G, Zhu X.-H, Zhou A.-X, Yang S.-D. Org. Chem. Front. 2018; 5: 232
• 18a Wang X.-Y, Zhong Y.-F, Mo Z.-Y, Wu S.-H, Xu Y.-L, Tang H.-T, Pan Y.-M. Adv. Synth. Catal. 2020; in press DOI: 10.1002/adsc.202001192.
• 18b He M.-X, Mo Z.-Y, Wang Z.-Q, Cheng S.-Y, Xie R.-R, Tang H.-T, Pan Y.-M. Org. Lett. 2020; 22: 724
• 18c Meng X.-J, Zhong P.-F, Wang Y.-M, Wang H.-S, Tang H.-T, Pan Y.-M. Adv. Synth. Catal. 2020; 362: 506
• 19 Kong X, Liu Y, Lin L, Chen Q, Xu B. Green Chem. 2019; 21: 3796
• 20 Mulina OM, Zhironkina NV, Paveliev SA, Demchuk DV, Terent’ev AO. Org. Lett. 2020; 22: 1818
• 21 Zhong P.-F, Lin H.-M, Wang L.-W, Mo Z.-Y, Meng X.-J, Tang H.-T, Pan Y.-M. Green Chem. 2020; 22: 6334
• 22 Ning Y, Zhao X.-F, Wu Y.-B, Bi X. Org. Lett. 2017; 19: 6240
• 23a Hassner A, Belinka BA. Jr. J. Am. Chem. Soc. 1980; 102: 6185
• 23b Kong X, Liu Y, Lin L, Chen Q, Xu B. Green Chem. 2019; 21: 3796
• 24 General Procedure for the Synthesis of gem-Bisphenylthio Enamine 3aa The azide 1a (0.3 mmol), thiophenol 2a (0.75 mmol), DBU (0.6 mmol), and TBAI (0.03 mmol) were placed in a 10 mL three-necked round-bottomed flask. The flask was equipped with a condenser and graphite rod as cathode and anode. MeOH (6.0 mL) was added. The electrolysis was carried out under air atmosphere at room temperature using a constant current of 3 mA until complete consumption of the substrate (monitored by TLC, about 1 h). The reaction mixture was concentrated, and the residue was chromatographed through silica gel eluting with ethyl acetate/petroleum ether to give the product 3aa.
• 25 Analytical Data for Compound 3aa 88% yield; yellow solid; mp 94.1–95.4 °C. Analytical TLC on silica gel. R_f = 0.48 (hexane/ether; 6.1). ¹H NMR (400 MHz, CDCl₃): δ = 8.19 (d, J = 8.4 Hz, 2 H), 7.66 (d, J = 8.4 Hz, 2 H), 7.22–7.17 (m, 2 H), 7.14–7.04 (m, 6 H), 5.04 (s, 2 H), 2.33 (s, 3 H), 2.31 (s, 3 H). ¹³C NMR (100 MHz, CDCl₃): δ = 158.0, 148.1, 143.8, 136.0, 135.3, 134.7, 131.8, 129.9, 129.7, 129.1, 127.8, 126.5, 123.5, 91.0, 21.0, 21.0. HRMS (ESI): m/z calcd for C₂₂H₂₁N₂O₂S₂ [M + H]⁺: 409.1039; found: 409.1036.