Enantiodivergent syntheses of γ-substituted butenolides with tertiary and quaternary asymmetric centers

Continuous nucleophilic addition with several organometallic reagents to tricyclic lactone (-)-1 proceeded diastereoselectively. Newly generated tertiary and quaternary asymmetric centers were controlled by the order in which the nucleophilic reagents were added. Using this methodology, enantiodivergent syntheses of several gamma-substituted butenolides with tertiary and quaternary asymmetric centers were established from a single chiral material. (C) 2003 Elsevier Science Ltd. All rights reserved.