Abstract
Spiroschincarins are triterpenoids characterized by a hexacyclic structure with a unique 1-oxaspiro[6.6]tridecanone skeleton and an all-cis substituted cyclopropane moiety. In the present study, this core skeleton was convergently synthesized by coupling all-cis-substituted cyclopropane and cycloheptanone fragments. The keys for its construction were the use of a conformationally limited substrate for lactonization and control of chelation for reducing the double bond on the spiro-lactone ring.