Synthesis And Novel Stereochemical Results In The Lithium–Ammonia Reduction Of Some 4-Alkyl-Δ1(9)-2-octalones

The 4-alkyl-Δ 1(9) -2-octalones 7–11, inclusive, prepared by conjugate addition of appropriate or ganocuprate reagents to the cross-conjugated dienones 13 and 14, were subjected to lithium–ammonia reduction. Interestingly, these reductions produced, in each case, a considerably higher proportion (13–35%) of the corresponding cis-fused 2-decalone (27–31, inclusive) as compared with that normally formed in the alkali metal – ammonia reduction of Δ 1(9) -2-octalones. The results are qualitatively explained in terms of the proposals originally set forth by Robinson.