The reaction of cyclohexanone (I) with acrylonitrile (II) by means of pyrrolidine gives 3-(2-oxocyclohexyl)propionitrile (III), which is condensed with methoxymethyltriphenylphosphonium chloride (IV) in THF to yield the methoxymethylene derivative (V). The condensation of propionitrile (V) with 4-bromostyrene (VI) by means of n-BuLi ethyl ether affords the styryl ketone (VII), which is cyclized by means of triphenyl phosphite and O3 (or air, methylene blue and light) to provide trioxane (VIII) as a diastereomeric mixture that is separated by column chromatography. Finally, the vinyl group of the desired diastereomer (VIII) is oxidized with KMnO4 in acetone to afford the target compound.

The cyclization of 3-[2-(methoxymethylene)cyclohexyl]-1-[4-(tert-butyldimethylsilyloxymethyl)phenyl]-1-propanone (I) by means of triphenyl phosphite and O3 gives the silylated trioxane (II), which is deprotected by means of TBAF to yield the hydroxymethyl derivative (III). Finally, this compound is oxidized with KMnO4 to afford the target compound.

The reaction of cyclohexanone (I) with acrylonitrile (II) by means of pyrrolidine gives 3-(2-oxocyclohexyl)propionitrile (III), which is condensed with methoxymethyltriphenylphosphonium chloride (IV) in THF to yield the methoxymethylene derivative (V). The condensation of propionitrile (V) with 4-bromostyrene (VI) by means of n-BuLi ethyl ether affords the styryl ketone (VII), which is cyclized by means of triphenyl phosphite and O3 (or air, methylene blue and light) to provide trioxane (VIII) as a diastereomeric mixture that is separated by column chromatography. Finally, the vinyl group of the desired diastereomer (VIII) is oxidized with KMnO4 in acetone to afford the target compound.