Total Synthesis of Principinol B.

ABSTRACT

We have accomplished the first and asymmetric total synthesis of principinol B, a grayanoid possessing an oxabicyclo[3.2.1] architecture. A functionalized 5/7/6/5 tetracyclic intermediate was assembled in a convergent manner by a diastereoselective intermolecular aldol reaction and subsequent carbonyl-olefin metathesis of two enantiomerically enriched fragments. The oxabicyclo[3.2.1] architecture containing a 6,10-ether bridge was constructed by the Williamson ether synthesis.