Intramolecular Michael-Aldol Condensation Approach to the Construction of Advanced Intermediates in the Synthesis of Forskolin

Article abstract of DOI:10.1021/jo00268a013

The tricyclic α,β-unsaturated ketone 6 has been elaborated from the β-keto ester 7c by using an intramolecular Michael addition (7c <*> 10), in tandem with an intramolecular aldol condensation (10 <*> 6).Starting from 6, the allylic alcohols 17a and 17b were prepared.The stereochemical features of 17a and 17b were determined by analysis of their NMR spectra and further confirmed by transformation of 17b into the known methyl ether 17c.Through a simple synthetic sequence, 17b was, in turn, converted to the known acetonide 19c.Compounds 17b and 19c are significant intermediates for the synthesis of forskolin (1).