Diastereoselective synthesis of fluorinated piperidine quinazoline spirocycles as iNOS selective inhibitors
作者:Chris Walpole、Ziping Liu、Ernest E. Lee、Hua Yang、Fei Zhou、Nicole Mackintosh、Magnus Sjogren、David Taylor、Jinyu Shen、Robert A. Batey
DOI:10.1016/j.tetlet.2012.03.050
日期:2012.6
A diastereoselective synthesis of fluoropiperidine quinazoline spirocycles has been developed through a silyl triflate mediated intermolecular coupling of difluorobenzamidine and racemic N-protected 3-fluoropiperidine dimethyl ketals or piperidones. Combination of the silyl reagents together with Lewis acids (such as BF3 center dot OEt2, ZnCl2, InCl3, etc.) accelerated the coupling reaction to afford the desired fluorospirocycies in good yields (40-83%) and high diastereoselectivity. A ratio of the two diastereoisomers of up to 10:1 in favor of the desired isomer can be achieved. (C) 2012 Published by Elsevier Ltd.