Biogenetically Patterned Enantioselective Synthesis

Bioenergetically oriented enantioselective syntheses of the bicyclic-ether substructure of Azadirachtin and of the spirocyclohexenone building block for the Agelorines are communicated. In the first case the kinetic resolution of a cyclopentenone starting material is exercised in a high pressure Diels-Alder cycloaddition and in the second case the cycloadduct of a prochiral spirocyclohexadienone is used for the differentiation of enantiotopic groups.