Highly Regioselective Carbamoylation of Electron-Deficient Nitrogen Heteroarenes with Hydrazinecarboxamides.

The use of hydrazinecarboxamides as a new class of carbamoylating agents has been established through the dehydrazinative Minisci reaction of electron-deficient nitrogen heteroarenes. A wide range of electron-deficient nitrogen heteroarenes, including isoquinoline, quinoline, pyridine, phenanthridine, quinoxaline, and phthalazine, underwent copper/acid-catalyzed oxidative carbamoylation with hydrazinecarboxamide hydrochlorides to afford structurally diverse nitrogen-heteroaryl carboxamides as single regioisomers in moderate to excellent yields. The functional group tolerance was substantially demonstrated in the direct carbamoylation of quinine obviating multistep sequences involving protecting groups and prefunctionalization of the heterocycle.