Synlett 2005(1): 158-160  
DOI: 10.1055/s-2004-835663
LETTER
© Georg Thieme Verlag Stuttgart · New York

Chemistry of Allylsulfones: A New Preparation of N-Diphenylmethylene-2-Vinyl-Substituted Cyclopropylamines

David Díez*a, P. Garcíaa, P. Fernándeza, Isidro S. Marcosa, N. M. Garridoa, P. Basabea, Howard B. Broughtonb, Julio G. Uronesa
a Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad de Salamanca, Plaza de los Caídos 1-5, 37008 Salamanca, Spain
b Lilly S.A., Avda. de la Industria 30, 28108 Alcobendas, Madrid, Spain
Fax: +34(923)294574; e-Mail: ddm@usal.es;
Further Information

Publication History

Received 30 July 2004
Publication Date:
29 November 2004 (online)

Abstract

A new methodology for the synthesis of N-diphenyl­methylene-2-vinyl-substituted cyclopropylamines, starting from the allylsulfone 11, is described. The starting material 11 can be ­obtained in both enantiomeric forms. The stereoselectivity of the cyclopropane formation has been studied by molecular modeling

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Data for Compound 19: [α]D 20 -76.8 (c 1.45, CHCl3). IR (film): νmax = 3058, 2928, 1446, 1317, 1145, 1086, 801 cm-1. 1H NMR (200 MHz, CDCl3): δ = 1.26 (m, 1 H, 3-Hα), 1.73 (dt, 1 H, J = 8.8, 4.4 Hz, 3-Hβ), 2.20 (m, 1 H, 2-H), 3.11 (ddd, 1 H, J = 4.4, 7.2, 9.2 Hz, 1-H), 6.33 (d, 1 H, J = 15.0 Hz, 2′-H), 6.46 (dd, 1 H, J = 9.2, 14.6 Hz, 1′-H), 7.10-7.61 (m, 13 H, Ar-), 7.84 (m, 2 H, H ortho , -SO2Ph). 13C NMR (50 MHz, CDCl3): δ = 19.8 (C-3), 26.1 (C-2), 46.3 (C-1), 127.4-129.1 (CH-Ar), 130.0 (C-2′), 133.1 (C para , -SO2Ph), 136.3 and 139.4 (C ipso , -Ph), 141.0 (C ipso , -SO2Ph), 148.1 (C-1′), 168.7 (CPh2). MS: m/z (%) = 388 (30) [MH+], 307 (15), 246 (35), 154 (100), 77 (55). HMRS: m/z calcd for C24H22NSO2: 388.1371; found: 388.1321 [MH+].

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The molecular modeling studies were carried out with Maestro v. 5.1.016 coupled to MacroModel v. 8.1.031, both supplied by Schrodinger, Inc. of Portland, OR, USA. Starting structures were built by sketching and were atom-typed automatically and energy-minimized using up to 5000 iterations of TNCG minimization to default convergence. The conformational search was carried out using the MCMM/Lowmode mixed method, with default settings based upon the automated setup procedure within Maestro. The conformational constraints were added manually and set to 25, 100 or 400 kJ/mol in three separate runs for each of the four models (cis- and trans-cyclopropane, and torsional constraint set to 0 or 180 degrees). The number of trials was set to 100 since at this value all the low-energy conformations were found at least 4 times. Minimizations were all achieved with up to 5000 iterations of TNCG optimization to default convergence, and all structures were successfully converged.