Abstract
A convenient four-step approach to the synthesis of (S)-4-alkyl-2-(pyrrolidin-2-yl)oxazoles starting from l-Boc-proline inspired by naturally occurring oxazole-containing peptidomimetics is described. The key step is the cyclization of 1-Boc-N-(1-oxoalkan-2-yl)pyrrolidine-2-carboxamides – aldehyde intermediates which demonstrate low to moderate stability – under Appel reaction conditions. This method furnishes the target compounds with more than 98% ee and in a 17–51% overall yield and has been used at up to a 45-g scale.
摘要:描述了一种从l-Boc-脯
氨酸获得灵感的天然存在含有
噁唑基肽类似物的合成(
S)-4-烷基-2-(
吡咯啉-2-基)
噁唑的便捷四步法。关键步骤是在Appel反应条件下,将1-Boc-
N-(1-氧代烷基)
吡咯啉-2-羧酰胺-醛中间体(表现出低至中等稳定性)环化。该方法以98%以上的
ee产率合成目标化合物,在17-51%的总产率下,可用于高达45克的规模。