A spontaneous bicyclization facilitates a synthesis of (−)-hispidospermidin

A concise, enantiospecific synthesis of the phospholipase C inhibitor (−)-hispidospermidin () has been achieved by approximating the architecture of a reactive intermediate that may lie on the biosynthetic pathway leading to this natural product. Two compounds derived from (R)-(+)-pulegone were joined by a highly diastereoselective carbonyl addition. A proximity-facilitated, acid-induced bicyclization of spiro[4.5]deca-1,7-diene gave rise to the tetracyclic framework of and was the key transformation in this synthesis.