Reaction between isocyanides and dialkyl acetylenedicarboxylates in the presence of 4,5-diphenyl-1,3-dihydro-2H-imidazol-2-one. One-pot synthesis of 5H-imidazo[2,1-b][1,3]oxazine derivatives

The reactive 1:1 intermediate produced in the reaction between alkyl or aryl isocyanides and dialkyl acetylenedicarboxylates was trapped by 4,5-diphenyl-1,3-dihydro-2H-imidazol-2-one to yield highly functionalized 2,3-diphenyl-5H-imidazo[2,1-b][1,3]oxazine derivatives in fairly good yields.