1,4-Addition of chiral 2-propenylphosphonamide anions to α-substituted cyclopentenones: use in enantioselective syntheses of methyl dihydrojasmonates and methyl jasmonates

The addition of chiral 2-propenylphosphonamide anions, generated from the reaction products of (1R,2S)-ephedrine and 2-propene-1-phosphonyl dichloride, to α-substituted cyclopentenones is described. Ozonolysis of the addition products led to the synthesis of both enantiomers of methyl dihydrojasmonate and methyl jasmonate.