Synthesis of conformationally constrained phenylalanine analogues via 7-, 8- and 9-endo Heck cyclisations

The novel conformationally constrained phenylalanine analogues 2,3,4,5-tetrahydro-1H-3-benzazepine-2-carboxylic acid (Sic) 1, 1,2,3,4,5,6-hexahydro-3-benzazocine-2-carboxylic acid (Hic) 2 and 2,3,4,5,6,7-hexahydro-1H-3-benzazonine-2-carboxylic acid (Nic) 3 have been synthesised from commercially available 2-iodobenzyl alcohol in 20, 18 and 22% overall yield respectively via 7-, 8- and 9-endo Heck cyclisations.