A Mild PPTS-Catalyzed Acetalization of α,β-Unsaturated Aldehydes: The First Single-Step Protocol towards Benzylic Acetals
摘要:
A mild and convenient procedure for the synthesis of highly sensitive benzylic acetals from alpha,beta-unsaturated aldehydes and the corresponding benzylic alcohols is reported. The new method provides a single-step access to these compounds for the first time. The applications of pyridinium p-toluenesulfonate (PPTS) as a very mild Bronsted acid catalyst and 5 angstrom molecular sieves (MS) as the dehydrating agent were found to be essential. Furthermore, an application of the acetals in the synthesis of 1-functionalized dienes is exemplified.