THEORETICAL-STUDY OF ETHYLENE AND VINYL ALCOHOL ADDITION TO 1,4-DIOXA-1,3-BUTADIENE

An ab initio theoretical study of the cycloaddition reaction between 1 ,4-dioxa-1,3-butadiene with ethylene and vinyl alcohol as dienophiles and borane as Lewis catalyst is presented. The geometries of the react ants and transition states were calculated at the RHF/3-21G and RHF/6- 31G level and the energies were estimated at the RMP2/6-31G*//RHF/6-3 1G level. The activation energies are compared to the all-carbon cycl oaddition reaction. The bond orders of the new forming bonds in the tr ansition state, the charge separation in the transition state, and the energy gap of the frontier orbitals correlate well with the activatio n barriers for these reactions. The relative reactivity of the reactan ts is discussed in terms of these parameters.