Intramolecular aza-Wittig ring closures were applied to synthesize thiazolines, oxazolines, and imidazolines from β-azido thioester, ester, and amide precursors. The cyclization precursors were obtained from amino acid derivatives. Optimized conditions for diazo transfer with a fast rate and racemization suppression, (thio)esterification, and amide coupling reactions are described. The ring closure reaction can
分子内 aza-Wittig 环闭合用于从 β-
叠氮基
硫酯、酯和酰胺前体合成
噻唑啉、
恶唑啉和
咪唑啉。环化前体是从
氨基酸衍
生物中获得的。描述了具有快速和外消旋化抑制、(
硫代)酯化和酰胺偶联反应的重氮转移的优化条件。闭环反应可以在中性条件下用 PPh3 进行,并且发现对五元环具有高度的
化学选择性。如果酰胺基团被
甲苯磺酰基激活,则亚
氨基膦的分子内闭环会提供具有位置特异性
甲苯磺酰基保护的对映纯
咪唑啉产品。