Asymmetric Aziridination of Chalcone Promoted by Binaphthalene-Based Chiral Amines

Abstract

Aminimines derived in situ from a number of enantiomerically pure binaphthalene-based tertiary amines have been used for the asymmetric aziridination of chalcone, providing N-unprotected aziridines with ee values of up to 43%. A chiral hydrazinium salt has been isolated for the first time and shown to provide similar yield and enantioselectivity to the in situ process in reaction with chalcone.

Key words

chalcone - aziridination - binaphthalene-based tertiary amines

• References and Notes


For an overview of aziridine chemistry, see:
• 1a Tanner D. Angew. Chem. Int. Ed. 1994; 33: 599
• 1b Sweeney JB. Chem. Soc. Rev. 2002; 31: 247
• 1c Hu XE. Tetrahedron 2004; 60: 2701
• 2 Osborn HM. I, Sweeney JB. Tetrahedron: Asymmetry 1997; 8: 1693
• 3 Pellissier H. Tetrahedron 2010; 66: 1509
• 4 Ikeda I, Machh Y, Okahara M. Synthesis 1980; 650
• 5 Armstrong A, Baxter CA, Lamont SG, Pape AR, Wincewicz R. Org. Lett. 2007; 9: 351
• 6 Shen YM, Zhao MX, Xu J, Shi Y. Angew. Chem. Int. Ed. 2006; 45: 8005
• 7 Armstrong A, Ferguson A. Beilstein J. Org. Chem. 2012; 8: 1747
• 8 Armstrong A, Pullin RD. C, Jenner CR, Scutt JN. J. Org. Chem. 2010; 75: 3499
• 9a Page PC. B, Buckley BR, Blacker AJ. Org. Lett. 2004; 6: 1543
• 9b Page PC. B, Farah MM, Buckley BR, Blacker AJ. J. Org. Chem. 2007; 72: 4424
• 9c Page PC. B, Farah MM, Buckley BR, Blacker AJ, Lacour J. Synlett 2008; 1381
• 9d Page PC. B, Buckley BR, Farah MM, Blacker AJ. Eur. J. Org. Chem. 2009; 3413
• 9e Page PC. B, Bartlett CJ, Chan Y, Day DP, Parker P, Buckley BR, Rassias GA, Slawin AM. Z, Allin SM, Lacour J, Pinto A. J. Org. Chem. 2012; 77: 6128
• 9f Farah MM, Page PC. B, Buckley BR, Blacker AJ, Elsegood MR. J. Tetrahedron 2013; 69: 758
• 10a Ohta T, Ito M, Inagaki K, Takaya H. Tetrahedron Lett. 1993; 34: 1615
• 10b Sengupta S, Leite M, Rasian DS, Quesnelle C, Snieckus V. J. Org. Chem. 1992; 57: 4066
• 10c Mecca T, Superchi S, Giorgio E, Rosini C. Tetrahedron: Asymmetry 2001; 12: 1225
• 10d Clyne DS, Jin J, Genest E, Gallucci JC, RajanBabu TV. Org. Lett. 2000; 2: 1125
• 11 Colvin EW, Kirby GW, Wilson AC. Tetrahedron Lett. 1982; 23: 3835
• 12 For the assignment of absolute configuration based on sign of optical rotation, see: Jin XL, Sugihara H, Daikai K, Tateishi H, Jin YZ, Furuno H, Inanaga J. Tetrahedron 2002; 58: 8321
• 13a Harada T, Kanda K. Org. Lett. 2006; 8: 3817
• 13b Ishihara K, Kurihara H, Matsumoto M, Yamamoto H. J. Am. Chem. Soc. 1998; 120: 6920
• 13c Zhang YL, Zhang F, Tang WJ, Wu QL, Fan QH. Synthesis 2006; 1250
• 14 Saha B, RajanBabu TV. J. Org. Chem. 2007; 72: 2357
• 15 Ooi T, Kameda M, Maruoka K. J. Am. Chem. Soc. 2003; 125: 5139
• 16 Denmark SE, Matsuhashi H. J. Org. Chem. 2002; 67: 3479
• 17 Prepared in 99% yield from the known diol by the action of PBr₃ in toluene at 70 °C over 3 h. See: Novikov R, Lacour J, Bernardinelli G. Adv. Synth. Catal. 2008; 350: 1113
• 18 For the preparation of MSH, see: Johnson CR, Kirchhoff RA, Corkins HG. J. Org. Chem. 1974; 39: 2458
• 19a Tamura Y, Minamikawa J, Kita Y, Kim JH, Ikeda M. Tetrahedron 1973; 29: 1063
• 19b Tamura Y, Minamikawa J, Ikeda M. Synthesis 1977; 1
• 20 Armstrong A, Carbery DR, Lamont SG, Pape AR, Wincewicz R. Synlett 2006; 2504
• 21 General Procedure with the in situ Hydrazinium Salt: The aminating agent (0.3 mmol) and base (0.6 mmol) were added to a stirred solution of the tertiary amine (0.2 mmol) in CH₂Cl₂ (4 mL). After stirring for 20 min at r.t., the chalcone substrate (0.2 mmol) was added as a solution in CH₂Cl₂ (1 mL). The reaction mixture was stirred for 48 h at r.t. Sat. aq NH₄Cl was added to the reaction mixture, and the organic phase was separated and washed sequentially with H₂O (3 × 10 mL) and brine (10 mL) before being dried (MgSO₄), filtered and concentrated in vacuo to give a crude residue that was purified by column chromatography [column packed with 5% Et₃N in petroleum ether and eluted with petroleum ether–EtOAc, (19:1)] to give the NH-aziridine as a colourless solid; mp 99–100 °C. IR: 3308, 3222, 3084, 3063, 3012, 2339, 1987, 1966, 1907, 1888, 1819, 1774, 1659, 1596, 1578 cm–1. ¹H NMR (300 MHz, CDCl₃): δ = 2.65–2.71 (br t, J = 8.0 Hz, 1 H, NH), 3.17 (br d, J = 8.0 Hz, 1 H, CHNH), 3.52 (br d, J = 7.0 Hz, 1 H, CHNH), 7.32–7.38 (m, 5 H, ArH), 7.48 (t, J = 8.0 Hz, 2 H, ArH), 7.62 (t, J = 7.0 Hz, 1 H, ArH), 8.00 (d, J = 7.0 Hz, 2 H, ArH). ¹³C NMR (75 MHz, CDCl₃): δ = 43.5, 44.0, 126.3, 128.0, 128.4, 128.6, 128.9, 133.9, 136.0, 138.4, 195.9.
• 22 General Procedure with the Preformed Hydrazinium Salt: The hydrazinium salt (0.2 mmol) and base (0.6 mmol) were dissolved in CH₂Cl₂ (4 mL) and stirred for 20 min at r.t. The chalcone substrate (0.2 mmol) was added as a solution in CH₂Cl₂ (1 mL). The reaction mixture was stirred for 48 h at r.t. Sat. aq NH₄Cl was added to the reaction mixture and the organic phase was separated and washed sequentially with H₂O (3 × 10 mL) and brine (10 mL) before being dried (MgSO₄), filtered and concentrated in vacuo to give a crude residue that was purified by column chromatography [column packed with 5% Et₃N in petroleum ether and eluted with petroleum ether–EtOAc (19:1)] to give the NH-aziridine as a colourless solid.