[3+3]-Cycloaddition Reactions of α-Acidic Isocyanides with 1,3-Dipolar Azomethine Imines

alpha-Acidic isocyanides are versatile reagents in organic synthesis, especially for the synthesis of five-membered heterocycles via [3 + 2]-cycloaddition reactions with activated multiple bonds. In this communication, the first [3 + 3]-cross-cycloaddition of alpha-acidic isocyanides with 1,3-dipolar azomethine imines to generate a series of 1,2,4-triazine derivatives with significant regiochemical control under mild catalytic reaction conditions is described. This new strategy shows that alpha-acidic isocyanides can also be taken as potent reagents for the synthesis of six-membered heterocycles through [3 + 3]-cross-cycIoaddition reactions with 1,3-dipoles.