Asymmetric Michael Addition Reactions of Chiral Prop-2-enyl- and But-2-enylphosphonate Anions with Cyclic Enones

Article abstract of DOI:10.1021/jo00129a051

Reactions of anions derived from chiral allyl- and crotylphosphonates with α,β-unsaturated cyclic ketones took place at the γ-position of the reagents and led to diastereomerically enriched products of conjugate addition, suggesting efficient enantiotopic face discrimination caused by remote asymmetric induction.Using mixtures of crotylphosphonates with different E/Z ratios, we found that the E/Z stereochemistry of the reagent was highly translated into the products.A tandem vicinal dialkylation based on Michael addition - enolate methylation was carried out to give the trans α,β-dialkylated product with high selectivity.Oxidative cleavage of the Michael adducts resulted in the formation of the optically active δ-keto aldehyde corresponding to the formal conjugate addition of an acetaldehyde or a propionaldehyde anion equivalent to α,β-unsaturated carbonyl compounds.