Application of force field calculations to organic chemistry. Part 6. Steric analysis of synthesis and structure of 1,4-dihydroxytricyclo-[6.4.0.0]dodecane-7,10-dione. Dynamic conformational calculations of its hydrocarbon skeleton and related systems (bicyclo[3.3.1]nonane and bicyclo[3.3.2]decane)

Abstract

The product distribution for the double intramolecular condensation of cyclododecanetetraone (3) has been calculated by the MM1 force field and found to explain the unexpected isolation of 1,4-dihydroxytricyclo[6.4.0.0,]dodecane-7,10-dione (1). Essential features of the detailed molecular structure of (1), as revealed by a previous X-ray analysis, can be reproduced by this force field. The hydrocarbon framework (9) of (1), which can be regarded as a triply fused twist-chair cyclohexane, an ethano-bridged cis-decalin, or a trimethylene-bridged bicyclo[3.3.1]nonane, was subjected to detailed static and dynamic conformational calculations by the MM2 force field and recognized to be in a deep energy well as is bicyclo[3.3.1]nonane. Similar calculations on the homologue bicyclo[3.3.2]decane reveal that a boat chair conformation (13c) with an eclipsed two-carbon bridge and a twin twist-chair (13a) with a staggered bridge coexist at equilibrium.