Ambident Reactivity of P˭CH‒N‒Heterocycles: Lithiation and Substitution Sites

Abstract

Benzofused 1H-1,3-azaphospholes are lithiated at the N-atom by tBuLi but phosphinylation takes place at either the N- or the P-atom. Smaller chlorophosphines react at nitrogen, bulkier react at phosphorus. Substituents at C2 promote the latter mode. N-Substituted 2H-1,3-benzazaphospholes undergo CH-metalation or addition at the P˭C bond, depending on the conditions, and allow access to 2-functionally substituted benzazaphospholes or their 2,3-dihydro derivatives, new σ²P,X or σ³P,X hybrid ligands (X=O,P).

Keywords:

• Ambident reactivity
• hybrid ligands
• lithiation
• phosphinylation
• phosphenes
• phosphorus heterocycles