Indium-Induced Addition of Bromomethylacrylates to Phthaloyl-Protected Amino Aldehydes
作者:Steffen Steurer、Joachim Podlech
DOI:10.1055/s-2002-28503
日期:——
The indium-mediated reaction of phthaloyl-protected α-amino aldehydes 1-4 with methyl 2-(bromomethyl)acrylate in aqueous solvents was investigated. The homoallyl alcohols 5-8 were formed in 72-89% yields, the anti-isomers being the major diastereoisomers (dr 45:55-18:82). Acid-catalyzed esterification (H2SO4 in Et2O) led to α-methylene γ-butyrolactones 9,10 with yields ranging from 88 to 99%. Conjugate addition of cyanide and thiophenolate led to the addition products with improved selectivities compared with additions to carbamate-protected substrates. During the conjugate addition of a cuprate, a trapping of the intermediate enolate by a phthaloyl carbonyl group occurred, leading to tetracycle 11 in 57% yield. The configuration of all diastereoisomers could be established by three X-ray crystallographic analyses and by NMR spectroscopy.
研究了在水溶剂中,邻苯二甲酰保护的α-氨基酸醛1-4与甲基2-(溴甲基)丙烯酸酯的铟介导反应。得到了同烯丙醇5-8,产率为72-89%,反式异构体为主要立体异构体(dr 45:55-18:82)。酸催化酯化(H2SO4在Et2O中)生成α-亚甲基γ-丁内酯9,10,产率范围为88至99%。氰化物和噻酚的共轭加成产物与加成到氨基甲酸酯保护的底物相比,选择性有所提高。在共轭加成铜试剂时,邻苯二甲酰羰基对中间体烯醇的捕获作用发生,导致了四环化合物11的生成,产率为57%。所有立体异构体的构型可以通过三次X射线晶体学分析和核磁共振波谱确定。