N-Heterocyclic Carbenes of Indazole as Reagents: Indazol-3-ylidene-Mediated Syntheses of Amidines from Thiolactams of Pyrrolobenzodiazepines

Abstract

On decarboxylation, 1,2-dimethylindazolium-3-carboxylate forms in situ the N-heterocyclic carbene 1,2-dimethylindazol-3-ylidene, which proved to be a suitable reagent for amidinations of the monothiolactam of benzo[e]pyrrolo[1,2-a][1,4]diazepine. A comparison of this metal-free approach to amidines to HgCl 2 -and Bi(NO 3 ) 3 -mediated reactions is presented.