Cleavage of 1,4-diketones on reduction with lithium in liquid ammonia. Conversion of cyclohexenone photodimers into the dihydrodimers

Abstract

A mechanism is discussed for cleavage of the central carbon–carbon bond in 1,4-diketones, (CO)C–C(CO), when this bond is orthogonal to the planes of the two carbonyl functions; lithium–ammonia–t-butyl alcohol reduction of the 1,4-diketonic photochemical dimers from isophorone and cyclohexenone gave in each case one stereoisomer of the corresponding dihydrodimers.