SEPARATION OF A MIXTURE OF R-MENTH-4-EN-3-ONE AND(-)-MENTHONE

摘要

A promising chiral synthon is R-menth-4-en-3-one(1)[1-4],which is produced from the natural monoterpenoid l-menthol through the intermediate(-)-menthone(2)[5,6]and is often contaminated(up to 10%)with the latter.The usual purification methods,including chromatographic ones,do not produce 1 of the desired purity.It is known [7]that 2 does not form bisulfites.Therefore,we supposed that it might be possible to isolate 1 from a mixture with 2 by forming the bisulfite derivative(3)of the ca^bonyl.According to our previous research [1],nucleophilic addition to 1 should occur via 1,2-addition to the carbonyl.Furthermore,the reaction was performed under the literature conditions [8,9]in order to prevent 1,4-addition of NaHSO_3.