Mn(III)-based oxidative free-radical 6-endo cyclizations of Z- trisubstituted alkenes

Article abstract of DOI:10.1016/S0040-4020(98)00612-7

Oxidative free-radical cyclization of Z-trisubstituted alkene 6a gave the expected octahydrophenanthrenes 9 (11%) and 10 (24%), lactone 17 (10%), and octahydrophenanthrene 4 (25%), which was obtained from E-trisubstituted alkene 1a. Cyclization of 6b provided the expected hydrindane 11 (25%), cyclopentane 18b (10%) formed by 5-exo cyclization, and hydrindane 5 (13%), which was obtained from E-trisubstituted alkene 1b. These results provide valuable information on the mechanism of Mn(III)-based oxidative radical cyclizations and indicate the profound effect of alkene geometry on the stereochemistry of radical cyclizations.