β‐Cleavage of Potassium Bicyclo[2.2.2]oct‐5‐en‐2‐olates. Stereoselective synthesis of (±)‐trichodiene

Abstract

Abstract The transformations of 12 bicyclo[2.2.2]oct‐5‐en‐2‐ols ( V or VI ) to 3‐(cyclohex‐3‐enyl)‐2‐alkanones ( III or IV ), via β‐cleavage of their potassium alkoxides in HMPA, has been investigated ( cf. Table 1 ). As an illustration of this synthetic methodology, a stereoselective synthesis of (±)‐trichodiene ((±)‐ 1 ) is described which involves the β‐cleavage of the tricyclic potassium alkoxides 46a and 47a to cyclopentanone 4 ( cf. Scheme 7 ).