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Thursday, 28 September 2017

Development of a General Protocol To Prepare 2H-1,3-Benzoxazine Derivatives

Figure
2H-1,3-Benzoxazine natural products and related bioactive molecules.

4-(2-Bromo-5-chlorobenzyl)-7-chloro-2-phenyl-2H-benzo[e][1,3]oxazine 2 as a light-yellow solid (82% yield).
1H NMR (500 MHz, CDCl3): δ (ppm) 7.55–7.52 (m, 3H), 7.42–7.34 (m, 3H), 7.30 (d, 1H, J = 3.5 Hz,) 7.29 (s, 1H), 7.12 (dd, 1H, J = 8.5 Hz, 2.5 Hz), 6.95–6.91 (m, 2H), 6.57 (1H, s), 4.16 (ABq, 2H, ΔδAB = 0.05, JAB = 16.5 Hz).
13C NMR (125 MHz, CDCl3): δ (ppm) 161.5, 155.8, 139.2, 138.9, 138.1, 133.8, 133.5, 130.6, 128.8, 128.7, 128.5, 127.0, 126.3, 122.6, 121.9, 117.3, 116.2, 88.9, 40.8.
HRMS TOF MS (m/z): [M + H]+ calcd for [C21H14BrCl2NO H] 445.9709; found 445.9713.
FTIR(neat): 3060, 1633, 1596, 1454, 1364, 1344 cm–1.
Spectroscopic data for 2 were identical to those reported in the literature.(4)
LiH.BelykK. M.YinJ.ChenQ.HydeA.JiY.OliverS.TudgeM.CampeauL.-C.CamposK. R. J. Am. Chem. Soc. 2015137,13728– 13731 DOI: 10.1021/jacs.5b05934

Development of a General Protocol To Prepare 2H-1,3-Benzoxazine Derivatives

 Department of Process Research and Development, MSD R&D (China) Co., Ltd., Building 21 Rongda Road, Wangjing R&D Base, Zhongguancun Electronic Zone West Zone, Beijing 100012, China
 Department of Process Research and Development, Merck Sharp & Dohme, Hertford Road, Hoddesdon, Hertfordshire EN11 9BU, United Kingdom
§ Department of Synthetic Chemistry, Pharmaron Beijing Co., Ltd., 6 Taihe Road BDA, Beijing, 100176, China
 Department of Process Research and Development, Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065, United States
Org. Process Res. Dev., Article ASAP
DOI: 10.1021/acs.oprd.7b00209
Publication Date (Web): August 23, 2017
Copyright © 2017 American Chemical Society
*E-mail: ji_qi@merck.com.
ACS Editors’ Choice – This is an open access article published under an ACS AuthorChoice License, which permits copying and redistribution of the article or any adaptations for non-commercial purposes.

Abstract

Abstract Image
A practical synthesis and detailed development process of 2H-1,3-benzoxazine derivatives catalyzed by aldimine and trifluoromethanesulfonic acid is described. A broad range of substrates with diverse steric and electronic properties were explored. Aliphatic/aromatic/heteroaromatic substrates all proceed well under conditions which have been optimized into a robust, scalable process.