HF/STO-3G analytic gradient method is used to calculate 8 structures of methylcyclopropylidene rearrangement reactions. These structures belong to 4 reaction types. The results show that hydrogen atom 1,3-shift of Me for carbene follow the end-on mechanism. The reaction activity of H atom 1, 2-shift on cyclopropyl ring obeys the rule; the smaller the angle between carbene carbon and CH, the larger the H shift activity.

Key words: REACTION MECHANISM, CARBENE, REARRANGEMENT REACTION, AB INITIO CALCULATION