ASYMMETRIC TOTAL SYNTHESIS OF TACAMONINE (PSEUDOVINCAMONE-I) VIA RADICAL CYCLIZATION

The radical cyclizations of -3-((2-(bromomethyl)butoxy)carbonyl)prop-2 -enoates 11 and 12 and (+/-)-ethyl romomethyl)butyl]-N-[2-(3-indolyl)e thyl]carbamoyl} prop-2-enoate (25) were carried out with (TMS)(3)SiH o r Bu(3)SnH in the presence of AIBN. )-2-((tert-Butyldimethylsilyloxy)m ethyl)butan-1-ol (6), which was prepared by two different methods, was converted into (+)-25. The radical cyclization of(+)-25 produced pipe ridinone 18 as a diastereomeric mixture, which was transformed into ta camonine (1).