Calculated heats of formation of sterol diene isomers compared with synthetic yields of isomerisation reactions of Δ5,7 sterols
Abstract
Heats of formation of five series of diene sterol isomers were calculated and compared with synthetic yields of acid-catalysed isomerisation reactions starting from Δ5,7 isomers. Calculations were based on molecular mechanics, using the MM3 program package. For each of the five Δ5,7 starting compounds, three possible reaction paths were considered, in which heats of formation were calculated for theoretically possible intermediate double bond isomers. Similar results are found for all five series. The starting compounds are found to have the unfavourable heats of formation compared to all other isomers considered within one series. In general, isomerisation reactions of diene