Computational study of ethylene,acetylene, and cyclopropene addition to heterocycles with two heteroatoms in the 1,2 position

The AM1 semiempirical and B3LYP density functional theory computational studies are undertaken with the target being to explore cycloaddition reactions with heterocycles that have two heteroatoms in the ring's 1 and 2 positions as an initial synthetic step in the preparation of allene's acetylene derivatives. Several qualitative computational approaches were used to evaluate the heterocycle reactivity, including two new approaches using electronic and bond order changes in transformation of the reactant pair into corresponding transition state structures. Finally, the reactivity was evaluated by computing activation barriers, and the feasibility of the proposed synthetic transformations was discussed.