Synthesis of benzo-fused, 7,5- and 7,6-fused azepinones as conformationally restricted dipeptide mimetics

Abstract Methodology for the generation of novel conformationally restricted dipeptide mimetics 9 and 16 has been developed. The key step involved intramolecular addition of an oxonium ion to the proximal indoline/tetrahydroquinoline aromatic ring. A dramatic difference in reactivity was observed in the formation of the 7,5- versus the 7,6-fused azepinone nuclei. Application of these mimetics in the synthesis of dual-acting ACE/NEP inhibitors 1 and 2 is described.