Enantioselective synthesis of a 3'-dephenylcryptophycin synthon

Article abstract of DOI:10.1016/S0960-894X(98)00557-5

An enantioselective synthesis of tert-butyl (5S,6R)-(E)-5-tert- butyldimethylsilyloxy-6-methyl-2,7-octadienoate, a precursor for the synthesis of the antimitotic macrolides cryptophycin A and arenastatin A (cryptophycin-24), is presented. The key step in the reaction sequence features a crotyl boration that sets both stereocenters that become the C16 hydroxyl and C1' methyl in the cryptophycins. Homologation of the terminal olefin via a Heck reaction is presented.