Phosphine-Mediated de Novo Arylamidation of α-Allylic Allenoates and Isocyanates via Bicyclo[3.1.0]hexene Access to Aryl Amides.

Amides are highly valuable structural units in pharmaceuticals and organic materials. Despite enormous progress in this field, de novo construction of aryl amides is underdeveloped. Here we present a phosphine-mediated arylamidine of α-allylic-substituted allenoates with isocyanates. This methodology features broad substrate scope, simple experimental operation, high efficiency, and good functional group tolerance. Isolation experiments on bicyclo[3.1.0]hexene, coupled with deuterium experiments, clarify a stepwise pathway involving ring-opening and aromatization processes, with the ring-opening step identified as crucial for achieving the aryl amides. The synthetic utility of this protocol has been further demonstrated by carrying out several downstream transformations and a concise formal synthesis of the benzene-1,3,5-tricarboxamide (BTA) molecule.