Synthesis of Trifluoromethylated Cycloheptatrienes from N-Tosylhydrazones: Transition-Metal-Free Büchner Ring Expansion

Abstract

A transition-metal-free Büchner reaction using trifluoromethylated N-tosylhydrazones as substrates is reported. A series of trifluoromethylated cycloheptatriene derivatives can be synthesized by this straightforward method.

Key words

diazo compounds - carbene - trifluoromethylation - Büchner reaction - cycloheptatriene

• References and Notes

• 1a Kirsch P. Modern Fluoroorganic Chemistry: Synthesis, Reactivity, Applications. Wiley-VCH; Weinheim: 2004
• 1b Gladysz JA, Curran DP, Horváth IT. Handbook of Fluorous Chemistry . Wiley-VCH; Weinheim: 2005
• 1c Horváth IT. Fluorous Chemistry . Springer; Berlin/Heidelberg: 2011
• 1d Müller K, Faeh C, Diederich F. Science 2007; 317: 1881
• 1e Furuya T, Kamlet AS, Ritter T. Nature (London, U.K.) 2011; 473: 470
• 1f Wang J, Sánchez-Roselló M, Aceña JL, del Pozo C, Sorochinsky AE, Fustero S, Soloshonok VA, Liu H. Chem. Rev. 2014; 114: 2432

For selected reviews, see:
• 2a Xu X.-H, Matsuzaki K, Shibata N. Chem. Rev. 2015; 115 in press; DOI: 10.1021/cr500193b
• 2b Ni C, Hu M, Hu J. Chem. Rev. 2015; 115 in press; DOI: 10.1021/cr5002386
• 2c Chu L, Qing F.-L. Acc. Chem. Res. 2014; 47: 1513
• 2d Zhu W, Wang J, Wang S, Gu Z, Aceña JL, Izawa K, Liu H, Soloshonok VA. J. Fluorine Chem. 2014; 167: 37
• 2e Chen P, Liu G. Synthesis 2013; 45: 2919
• 2f Liang T, Neumann CN, Ritter T. Angew. Chem. Int. Ed. 2013; 52: 8214
• 2g Liu H, Gu Z, Jiang X. Adv. Synth. Catal. 2013; 355: 617
• 2h Studer A. Angew. Chem. Int. Ed. 2012; 51: 8950
• 2i Wu X.-F, Neumann H, Beller M. Chem. Asian J. 2012; 7: 1744
• 2j Liu T, Shen Q. Eur. J. Org. Chem. 2012; 6679
• 2k Macé Y, Magnier E. Eur. J. Org. Chem. 2012; 2479
• 2l García-Monforte MA, Martínez-Salvador S, Menjón B. Eur. J. Inorg. Chem. 2012; 4945
• 2m Tomashenko OA, Grushin VV. Chem. Rev. 2011; 111: 4475
• 2n Zheng Y, Ma J.-A. Adv. Synth. Catal. 2010; 352: 2745
• 2o Grushin VV. Acc. Chem. Res. 2009; 43: 160
• 2p Cahard D, Ma J.-A. Chem. Rev. 2008; 108: PR1
• 2q Kirk KL. Org. Process Res. Dev. 2008; 12: 305
• 2r Shibata N, Mizuta S, Kawai H. Tetrahedron: Asymmetry 2008; 19: 2633
• 2s Ma J.-A, Cahard D. J. Fluorine Chem. 2007; 128: 975
• 2t Prakash GK. S, Hu J. Acc. Chem. Res. 2007; 40: 921
• 2u Mizuta S, Shibata N, Hibino M, Nagano S, Nakamura S, Toru T. Tetrahedron 2007; 63: 8521
• 2v Ma J.-A, Cahard D. Chem. Rev. 2004; 104: 6119
• 2w Prakash GK. S, Yudin AK. Chem. Rev. 1997; 97: 757

For selected reviews on the reaction of diazo compounds, see:
• 3a Ye T, McKervey MA. Chem. Rev. 1994; 94: 1091
• 3b Doyle MP, McKervey MA, Ye T. Modern Catalytic Methods for Organic Synthesis with Diazo Compounds. Wiley; New York: 1998
• 3c Zhang Z, Wang J. Tetrahedron 2008; 64: 6577
• 4 Denton JR, Sukumaran D, Davies HM. L. Org. Lett. 2007; 9: 2625
• 5 Uehara M, Suematsu H, Yasutomi Y, Katsuki K. J. Am. Chem. Soc. 2011; 133: 170
• 6 Wang X, Xu Y, Deng Y, Zhou Y, Feng J, Ji G, Zhang Y, Wang J. Chem. Eur. J. 2014; 20: 961
• 7 Jiménez-Aquino A, Vega JA, Trabanco AA, Valdés C. Adv. Synth. Catal. 2014; 356: 1079
• 8a Barluenga J, Valdés C. Angew. Chem. Int. Ed. 2011; 50: 7486
• 8b Shao Z, Zhang H. Chem. Soc. Rev. 2012; 41: 560
• 8c Xiao Q, Zhang Y, Wang J. Acc. Chem. Res. 2013; 46: 236
• 9a Duddeck H, Kennedy M, McKervey MA, Twohig FM. J. Chem. Soc., Chem. Commun. 1988; 1586
• 9b Moody CJ, Miah S, Slawin AM. Z, Mansfleld DJ, Richards IC. J. Chem. Soc., Perkin Trans. 1 1988; 4067
• 9c Doyle MP, Ene DG, Forbes DC, Pillow TH. Chem. Commun. 1999; 1691
• 9d Padwa A, Austin DJ, Price AT, Semones MA, Doyle MP, Protopopova MN, Winchester WR, Tran A. J. Am. Chem. Soc. 1993; 115: 8669
• 9e Cordi AA, Lacoste J.-M, Hennig P. J. Chem. Soc., Perkin Trans. 1 1993; 3
• 9f Merlic CA, Zechman AL, Miller MM. J. Am. Chem. Soc. 2001; 123: 11101
• 9g Doyle MP, Hu W, Timmons DJ. Org. Lett. 2001; 3: 933
• 9h Doyle MP, Phillips IM. Tetrahedron Lett. 2001; 42: 3155
• 9i Kane JL, Shea KM, Crombie AL, Danheiser RL. Org. Lett. 2011; 3: 1081
• 10 Brunner J, Serin H, Richards FM. J. Biol. Chem. 1980; 255: 3313
• 11 General Procedure for the Büchner ReactionIn an oven-dried 20 mL Schlenk tube, N-tosylhydrazone (1, 0.2 mmol, 1.0 equiv), Cs₂CO₃ (0.6 mmol, 3 equiv), and 4 Å MS were added. Then the tube was sealed with a septum, and degassed by alternating vacuum evacuation and nitrogen backfill (3×) before benzene (4 mL) was added. The reaction was then stirred at 120 °C for 3 h. The reaction mixture was cooled to r.t. and filtered through a short plug of silica gel with Et₂O as eluents. Solvent was then removed in vacuo to leave a crude mixture, which was purified by preparative TLC to afford pure products.7-Phenyl-7-(trifluoromethyl)cyclohepta-1,3,5-triene (3a) ¹H NMR (400 MHz, CDCl₃): δ = 7.26 (d, J = 7.4 Hz, 2 H), 7.18–7.09 (m, 3 H), 6.44–6.42 (m, 2 H), 6.30–6.28 (m, 2 H), 5.72 (d, J = 9.3 Hz, 2 H). ¹³C NMR (101 MHz, CDCl₃): δ = 134.9, 130.2, 129.8, 127.8, 127.1 (q, J = 281.9 Hz), 126.6, 126.6, 117.3, 53.2 (q, J = 25.0 Hz). ¹⁹F NMR (470 MHz, CDCl₃): δ = –74.3 (s, 3 F). MS (EI): m/z (%) = 236 (66) [M⁺], 215 (15), 167 (100), 165 (60), 152 (28). IR (film): 1284, 1188, 1151, 978, 687 cm^–1. HRMS (EI): m/z calcd for C₁₄H₁₁F₃ [M]⁺: 236.0807; found: 236.0815.