Application of radical cyclisation/iodine atom transfer to the chiral synthesis of (-)-methylenolactocin

Article abstract of DOI:10.1016/0040-4020(95)00673-V

Methylenolactocin, an antitumour antibiotic, has been synthesized through an efficient radical cyclisation process on a chiral iodo acetylene ester. Chiral iodohydrins may be formed by regioselective opening of a chiral epoxy ester, prepared by Sharpless epoxidation. C-2 opening is achieved with TMSCl/NaI and C-3 attack with MgI₂. Subsequent esterification of the 2-iodo compound by reaction with substituted propynoyl triflates gives the key iodo acetylenic esters. This route is highly adaptable to the synthesis of analogues.