Application of 7-endo, 8-endo and 9-endo radical cyclisations 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 respectively; comparison of these results with those obtained using the intramolecular Heck reactions suggests that the two cyclisation methods provide complementary approaches to medium-sized rings.