Investigation of the Mechanism of reductive dehalogenation of haloanisoles under aryne-forming conditions

Abstract

Separation of the reductive dehalogenation mechanism proceeding via aryne (mechanism A) from direct halogen displacement mechanisms (mechanisms B and C) has been achieved. In the presence of large excesses of di-npropylamine as compared with lithium di-n-propylamide and haloanisole, aryne reduction is essentially eliminated. With the exception of o-and p-iodoanisole, haloanisole appears to undergo nonaryne reduction via mechanism B, hydride attack on ring halogen. Mechanism C, amide ion nucleophilic attack on ring halogen, most likely operates in the reduction of o-and p-iodoanisole. An explanation in terms of the influence of the methoxy group on (a) Results