Synthesis of heterocyclic-fused imidazoles by pyrolysis of N-heterocyclic isoxazol-5(2H)-ones

The synthesis of heterocyclic-fused imidazoles was achieved by flash vacuum pyrolysis (FVP) of N-heterocyclic isoxazol- 5(2H)-ones via an iminocarbene intermediate. Unlike iminocarbenes generated from triazoles, no structural rearrangements were observed during the current synthesis method. We also demonstrated that less volatile isoxazol-5(2H)-one derivatives yield the corresponding imidazoles by condensed phase pyrolysis.