APPLICATION OF 7-ENDO, 8-ENDO AND 9-ENDO RADICAL CYCLIZATIONS TO THE SYNTHESIS OF CONFORMATIONALLY CONSTRAINED AMINO-ACIDS AND COMPARISON WITH THE CORRESPONDING HECK REACTIONS

Radical cyclisation of substrates 1a-c proceeds smoothly to give seven -, eight- and nine-membered rings 3a-c in 73, 71 and 52% yield respect ively; comparison of these results with those obtained using the intra molecular Heck reactions suggests that the two cyclisation methods pro vide complementary approaches to medium-sized rings.