Synthesis 2011(4): 585-592  
DOI: 10.1055/s-0030-1258406
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

A Modified Synthetic Approach to Optically Pure Benzoxazepines from Amino Acid Precursors Using Intramolecular Buchwald-Hartwig C-O Bond-Formation Reaction

Debleena Bhattacharya, Ashok Behera, Sandip K. Hota, Partha Chattopadhyay*
Department of Chemistry, Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Kolkata 700 032, India
Fax: +91(33)24735197; e-Mail: partha@iicb.res.in;
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Publication History

Received 15 November 2010
Publication Date:
12 January 2011 (online)

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Abstract

Palladium-catalyzed intramolecular aryl etherification reaction using bulky binaphthylphosphane ligand is shown to be a convenient method for the synthesis of seven-membered heterocycles. Application of this methodology to a naturally occurring proteinogenic l-amino acid has led to the synthesis of optically active benzoxazepine ring systems of versatile biological importance.

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Crystal data of compound 8g: C20H25NO4S, FW = 375.47, triclinic, space group P1, a = 6.687(4) Å, b = 7.508(5) Å, c = 10.114(6) Å, α = 75.93(4)˚, β = 88.29(4)˚, γ = 80.28(4)˚, V = 485.4(5) ų, Z = 1, T = 296(2) K, d calcd = 1.284 g cm, F(000) = 200. Diffraction data were measured with Mo-Kα (λ = 0.71073 Å) radiation at 296 K using a Bruker Kappa Apex 2 CCD system. A total of 2595 unique reflections were measured (θmax = 28.18˚). Data analyses were carried out with the Fast Fourier Transform program. The structures were solved by direct methods using the SHELXS-97²² program. Refinements were carried out with a full matrix least squares method against F2 using SHELXL-97.²³ Non-hydrogen atoms were refined with anisotropic thermal parameters. The final R value was R1 = 0.0479 and wR2 = 0.1255 with I > 2σ(I). Crystallographic data have been deposited at the Cambridge Crystallographic Data Centre with reference numbers CCDC 776221. These data can be obtained free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44(1223)336033, E-mail: deposit@ccdc.cam.ac.uk].