Metal‐Free Decarboxylative Cyclization/Ring Expansion: Construction of Five‐, Six‐, and Seven‐Membered Heterocycles from 2‐Alkynyl Benzaldehydes and Cyclic Amino Acids

A one pot synthesis of 1H-benzo[g]indoles, tetrahydrobenzo[h]quinolines, and naphtho[1,2-b]azepines from 2-alkynyl benzaldehydes and cyclic amino acids is reported. The salient feature of the strategy involves formation of three new bonds (one CN and two CC bonds) by a metal-free decarboxylation/cyclization/one-carbon ring expansion sequence in one pot.