The total synthesis of (−)-aplysin via a lithiation-borylation-propenylation sequence

A concise, highly enantioselective synthesis of sesquiterpene natural products (−)-debromoaplysin and (−)-aplysin has been completed. The key steps included lithiation-borylation of a secondary benzylic carbamate to give a tertiary boronic ester followed by propenylation which installed the quaternary stereocenter with complete enantioselectivity. Subsequent RCM followed by deprotection and in situ cyclization led to debromoaplysin with good diastereoselectivity from which the target compound was prepared in just eight overall steps.