Quantum-chemical calculation as an aid in synthesis of prostaglandins, attempt of prediction of relative stability of four stereoisomeric methyl 7-hydroxy-2-oxa-3-oxobicyclo[3.3.0]octane-6-carboxylates

Partial optimization of conformation structure of quantum-chemical models of the stereoisomeric lactones I to IV has been carried out by the CNDO/2 method. The calculated energy characteristic and electron distributions have been used for discussion of some factors affecting retention of 5,6-trans-configuration in the key intermediate of prostaglandin syntheses (formulaI) with regard to conditions of the preparative experiments.