The oxidation of (5R)-(-)-carvone (I) with 3-chloroperbenzoic acid (3-CPB) in dichloromethane gives 5(R)-acetyl-2-methyl-2-cyclohexen-1-one (II), which is condensed with ethyltriphenylphosphonium bromide (III) by means of butyllithium in THF yielding 2-methyl-5(Z)-(1-methyl-1-propenyl)-2-cyclohexen-1-one (IV). The photochemical oxidation of (IV) in acetonitrile catalyzed by methylene blue affords (1R,4RS,5R,8S)-4,8-dimethyl-4-vinyl-2,3-dioxabicyclo[3.3.1]nonan-7-one (V), which is ozonolyzed with O3 in methanol to the corresponding aldehyde as a mixture of enantiomers, which is submitted to crystallization giving the (1S,4R,5R,8S)-isomer (VI). Finally, this compound is submitted to a Wittig condensation with 2,4-bis(trifluoromethyl)benzyltriphenylphosphonium bromide (VII) by means of sodium bis(trimethylsilyl)amide (NaBTSA) in dichloromethane.

The oxidation of (5R)-(-)-carvone (I) with 3-chloroperbenzoic acid (3-CPB) in dichloromethane gives 5(R)-acetyl-2-methyl-2-cyclohexen-1-one (II), which is condensed with ethyltriphenylphosphonium bromide (III) by means of butyllithium in THF yielding 2-methyl-5(Z)-(1-methyl-1-propenyl)-2-cyclohexen-1-one (IV). The photochemical oxidation of (IV) in acetonitrile catalyzed by methylene blue affords (1R,4RS,5R,8S)-4,8-dimethyl-4-vinyl-2,3-dioxabicyclo[3.3.1]nonan-7-one (V), which is ozonolyzed with O3 in methanol to the corresponding aldehyde as a mixture of enantiomers, which is submitted to crystallization giving the (1S,4R,5R,8S)-isomer (VI). Finally, this compound is submitted to a Wittig condensation with 2,4-bis(trifluoromethyl)benzyltriphenylphosphonium bromide (VII) by means of sodium bis(trimethylsilyl)amide (NaBTSA) in dichloromethane.

The oxidation of (5R)-(-)-carvone (I) with 3-chloroperbenzoic acid (3-CPB) in dichloromethane gives 5(R)-acetyl-2-methyl-2-cyclohexen-1-one (II), which is condensed with ethyltriphenylphosphonium bromide (III) by means of butyllithium in THF yielding 2-methyl-5(Z)-(1-methyl-1-propenyl)-2-cyclohexen-1-one (IV). The photochemical oxidation of (IV) in acetonitrile catalyzed by methylene blue affords (1R,4RS,5R,8S)-4,8-dimethyl-4-vinyl-2,3-dioxabicyclo[3.3.1]nonan-7-one (V), which is ozonolyzed with O3 in methanol to the corresponding aldehyde as a mixture of enantiomers, which is submitted to crystallization giving the (1S,4R,5R,8S)-isomer (VI). Finally, this compound is submitted to a Wittig condensation with 2,4-bis(trifluoromethyl)benzyltriphenylphosphonium bromide (VII) by means of sodium bis(trimethylsilyl)amide (NaBTSA) in dichloromethane.