Fig. 3. (a) Selected structures of naturally occurring and biologically active terpenoids containing γ-substituted, cis-fused bicyclic-γ-lactones. (b) Comparison of conventional strategies employing optically active dienyl alcohols 7 or enzymatic resolution and the described DAL organocascade to access bicyclic γ- and δ-lactones 11 (n = 0, 1). Use of racemic dienes (±)-7 bearing a pendant carbinol stereocenter (blue circle) enables a stereodivergent organocascade that introduces up to four additional stereocenters (blue asterisk) through catalyst control independent of the resident carbinol stereocenter.
