α,β-unsaturated δ-lactones from copper-catalyzed asymmetric vinylogous mukaiyama reactions of aldehydes: Scope and mechanistic insights
A direct regio-, diastereo-, and enantiocontrolled access to α,β-unsaturated δ-lactones is described, based on the reaction of a silyl dienolate and an aldehyde in the presence of 10% of Carreira's catalyst. The scope and limitations of this reaction, as well as mechanistic insights concerning the reactivity of an allyl copper species, are discussed.
Enantioselective Synthesis of γ,δ-Disubstituted β-Hydroxy δ-Lactones from Furans: Synthesis of (+)-Prelactone B and its C-4 Epimer
A new method for the enantioselective synthesis of γ,δ- disubstituted β-hydroxy δ-lactones (5,6-dialkyl-5,6-dihydropyran-2- ones) is reported and exemplified for (+)-prelactone B and its C-4 epimer. Our approach is based on the ring-enlargement of suitably functionalized optically pure 4-hydroxycyclopentanones, which are readily obtained from chiral 4-hydroxycyclopent-2-enones derived from furans. The procedure is amenable to the large-scale synthesis of the title compounds.
Csák?, Aurelio G.,Mba, Myriam,Plumet, Joaquín
p. 2092 - 2094
(2007/10/03)
Catalytic asymmetric access to α,β unsaturated δ-lactones through a vinylogous aldol reaction: Application to the total synthesis of the Prelog-Djerassi lactone
Figure presented A one-step catalytic asymmetric access to α,β unsaturated δ-lactones is described, using a vinylogous Mukaiyama-aldol reaction between a γ-substituted dienolate and various aldehydes in the presence of Carreira catalyst CuF·(S)-tolBinap.