Total synthesis of (+)-pinnatoxin A.

A convergent enantioselective total synthesis of (+)-pinnatoxin A is described. The synthesis capitalizes on the highly diastereoselective Ireland-Claisen rearrangement of an acyclic alpha-branched allylic ester to set the quaternary stereogenic center at the core of the spiroimine ring system along with the adjacent tertiary stereocenter. The all-carbon macrocyclic ring system was formed by ring-closing metathesis.