Diastereoselective radical cyclization using a chiral α-methyl-α,β-unsaturated ester: Controlling the stereochemistry at both the α- and β-positions

Article abstract of DOI:10.1016/0957-4166(95)00350-X

Diastereoselective radical cyclizations of (-)-8-phenylmenthyl 2-methyl-2-octene-7-ynoate (9) and (-)-8-phenylmenthyl 7-iodo-2-methyl-2,7-octadienoate (10) were investigated. The best results were obtained in the cyclization of 10 at -98°C. A mixture of four diastereomers was obtained at a yield of 72% and with a diastereoselectivity of 78:12:9.1. The main product was (S)-2-[(R)-2-methylene-cyclopentyl]propionate (3a). The diastereoselectivities at the α- and β-positions were 90:10 and 79:21, respectively.