No abstract

A robust and versatile kinetic alkylation-ozonolysis procedure, previously used for the synthesis of 2-alkyl-2-cyclopenten-1-ones and racemic γ-substituted-γ-lactones, has now been applied to the synthesis of chiral γ-substituted-γ-lactones and δ-substituted-δ-lactones. In addition to the synthesis of lactones with simple alkyl substituents, the method allows terminal ester and halogen groups, and an alkyne bond to be incorporated into the side chain.

The Copper Mediated Barbier Reactions of α,β-Unsaturated Ketones: Regioselective Conjugate and 1,2-Addition.-The one-pot reaction of isophorone (I) and other α,β-unsaturated ketones such as (V) and (VII) with alkyl and aryl halides (II) in the presence of magnesium and copper salts (Barbier conditions) leads to the regiospecific formation of 1,4-addition products. Contrary, Li-mediated reaction of model compound (I) with halides (II) results in regioselective 1,2-addition [→(IV)]. -(COSTELLO, DECLAN P.; GERAGHTY, NIALL W. A.; Synth. Commun. 29 (1999) 18, 3083-3096; Chem. Dep., Nat. Univ. Ire., Galway, Ire.; EN)