CONFORMATION DYNAMICS OF 1,2-DIMETHYLENECYCLOHEXANE - A MODEL FOR RING-A MOBILITY IN VITAMINS-D

The conformation dynamics of 1,2-dimethylenecyclohexane was examined by means of ab initio MO theory employing the STO-3G and 3-21G basis sets. The calculations show that the most economic mode of chair-chair interconversion begins with inversion of twist angles in the diene part of the chairlike minimum conformation and proceeds via pseudorotation and reinversion to the alternate chair. The results are discussed in relation to the ring A structure and mobility of vitamins D. © 1990, American Chemical Society. All rights reserved.