Formal Total Synthesis of (+)-Trehazolin. Application of an Asymmetric Aldol−Olefin Metathesis Approach to the Synthesis of Functionalized Cyclopentenes

An asymmetric synthesis of the aminocyclopentitol pseudosugar of trehazolin has been completed. The synthesis hinges on an asymmetric aldol-ring closing metathesis strategy to construct the five-membered ring with control of both the relative and absolute stereochemistry.