Azaindole synthesis through dual activation catalysis with N-heterocyclic carbenes

Abstract

A convergent, transition-metal-free synthesis of 2-aryla-zaindoles has been developed. The interception of a reactive aza-ortho-azaquinone methide intermediate by an acyl anion equivalent generated through carbene catalysis provides high yields, a wide substrate scope, and the synthesis of previously inaccessible azaindoles.

Synthesis of Fused‐Pyrazines via Palladium‐Catalyzed Double Benzyl Isocyanide Insertion and Cross‐Dehydrogenative Coupling

“…In 2012, Keivanloo et al improved the yield of aloisines by modifying the conditions of Hopkins using the combination of Pd‐Cu in the presence of SDS surfactant in water . Recently, in 2016, Scheidt et al disclosed a couple of examples through an interception of a reactive aza ortho ‐azaquinone methide intermediate by an acyl anion equivalent generated through carbene catalysis (Scheme d) …”

A [4 + 3] Annulation Reaction of aza-o-Quinone Methides with Arylcarbohydrazonoyl Chlorides for Synthesis of 2,3-Dihydro-1H-benzo[e][1,2,4]triazepines

“…In comparison with [4 + 2] cycloadditions, other types of cycloaddition reactions involving ao-QMs are quite limited. One of these limited examples was the [4 + 1] annulation reaction of ao-QMs generated in situ with sulfur ylides, affording indole products . Other examples focused on [4 + 3] cycloaddition reactions.…”