(R)-(+)-Limonene (I) is subjected to a free-radical sequential thiol-olefin cooxygenation in the presence of O2, thiophenol and di-tert-butyl peroxalate (DBPO) to furnish the sulfenyl endoperoxide (II) as a mixture of diastereoisomers. Chemoselective reduction of the hydroperoxide function of (II) with PPh3 yields alcohol (III). After oxidation of the sulfenyl group of (III) to the corresponding sulfone with mCPBA, the required isomer (IV) is isolated employing medium-pressure liquid chromatography. Finally, treatment of alcohol (IV) with phenyldiazomethane in the presence of trifluoromethanesulfonic acid gives rise to the O-benzylated derivative (1,2).

(R)-(+)-Limonene (I) is subjected to a free-radical sequential thiol-olefin cooxygenation in the presence of O2, thiophenol and di-tert-butyl peroxalate (DBPO) to furnish the sulfenyl endoperoxide (II) as a mixture of diastereoisomers. Chemoselective reduction of the hydroperoxide function of (II) with PPh3 yields alcohol (III). After oxidation of the sulfenyl group of (III) to the corresponding sulfone with mCPBA, the required isomer (IV) is isolated employing medium-pressure liquid chromatography. Finally, treatment of alcohol (IV) with phenyldiazomethane in the presence of trifluoromethanesulfonic acid gives rise to the O-benzylated derivative (1,2).