SYN-ANTI ISOMERISM IN THE REACTIONS OF CIS-3,4-DISUBSTITUTED CYCLOBUTENES .7. HF/3-21G TRANSITION STRUCTURES OF THE REACTION OF DIAZOMETHANE WITH CIS-3,4-DICHLOROCYCLOBUTENE

Transition structures for the syn and anti attack of diazomethane on cis-3,4-dichlorocyclobutene have been obtained with the HF/3-21 G model. These calculations correctly predict the dominance of syn attack. Analysis of the activation energy shows that the inherent facial bias of dichlorocyclobutene is reflected, at the transition state, in the deformation energy of both dichlorocyclobutene and diazomethane and in the interaction energy between them.