Niobium(V) chloride-mediated allylation of aldehydes.Scope and stereoselectivity

摘要

Niobium chloride promoted the addition of allylstannanes to aromatic and aliphatic aldehydes.Excellent syn diastereoselectivity was obtained in the addition of E-cinnamylstannane to benzaldehyde (49:1).In the addition of allylstannane to racemic 2-phenylpropionaldehyde,syn diastereoselection (Cram-anti-Cram=3:1) was observed.The same level of diastereoselection was achieved in the reaction between crotylstannane and benzaldehyde.