The reductive aldol reaction of electron deficient aromatic compounds has been investigated and found to be a viable method for carbon–carbon bond formation. Reductions under ammonia and ammonia-free conditions were both capable of facilitating the aldol reaction although the latter showed more scope for reaction with enolisable aldehydes. Moreover, reduction under ammonia-free conditions allowed the addition of Lewis acids which improved stereoselectivity to favour the anti stereoisomer. Production of the syn diastereoisomer was possible through either one of two different protocols performed after partial reduction was complete. While the main emphasis of this paper concerns the reductive aldol reaction of electron deficient pyrroles, it was also shown that both benzenoid and furan aromatic compounds were amenable to such reducing conditions.
研究发现,缺电子芳香化合物的还原醛醇反应是碳-碳键形成的一种可行方法。
氨和无
氨条件下的还原反应都能促进醛醇反应,但后者在与可烯化的醛反应中表现出更大的空间。此外,在无
氨条件下还原可以加入
路易斯酸,从而提高立体选择性,有利于反立体异构体。在部分还原完成后,可以通过两种不同方案中的一种来生产合成非对映异构体。本文的主要重点是缺电子
吡咯的还原性醛醇反应,但同时也证明了苯类和
呋喃类芳香化合物也适用于这种还原条件。