The convergent syntheses of pyrazinyl and quinoxalinyl phenylmethanones from 2‐lithio pyrazines and quinoxalines

Abstract

Abstract Pyrazines and quinoxalines bearing 2‐substituents that direct ortho metalation reacted with lithium 2,2,6,6‐tetramethylpiperidide to produce 2‐substituted‐3‐lithiopyrazines and quinoxalines. These lithio reagents reacted with N ‐methoxy‐ N ‐methylbenzamide to give good to moderate yields of 3‐substituted pyrazinyl or quinoxalinylphenylmethanones. The 3‐methylthio substituents of some ketone products were oxidized to methylsulfonyl groups that were susceptible to nucleophilic displacement.