Generation, structure and reactivity of arynes: A theoretical study

The semiempirical AMI SCF-MO method is used to study the benzyne mechanism for aromatic nucleophilic substitution of various m-substituted chlorobenzenes and 3-chloropyridine. The calculations predict that most of the fixed substituents studied here would induce the formation of 2,3-arynes through their electron-withdrawing resonance or inductive effects. The geometry and electronic structure of the 2,3- and 3,4-arynes investigated here, confirm the generally accepted a-benzyne structure postulated for arynes. The sites of nucleophilic addition to arynes as predicted here are in fair agreement with expectation and experimental findings.