Multicomponent synthesis of substituted and fused-ring imidazoles via phospha-münchnone cycloaddition.

A new, one-pot synthesis of imidazoles from imines, acid chlorides, and N-nosyl imines or tethered nitriles is reported. The reaction is mediated by the phosphonite PPh(catechyl) and proceeds via regioselective cycloaddition with an in situ-generated phospha-münchnone 1,3-dipole. This provides an efficient route to construct both highly substituted and polycyclic imidazoles directly from available substrates, without metal catalysts, and with access to product diversity.