New Routes to cis-Jasmone and Dihydrojasmone via 1,4-Diketones Exploiting the Mobile Activating Sulfonyl Group

Article abstract of DOI:10.1021/jo01308a011

cis-Jasmone(1a) and dihydrojasmone(1b) are synthesized starting from cis-3-hexen-1-yl phenyl sulfone (6a) and n-hexyl phenyl sulfone (6b), respectively, through 1,4-diketones 3a,b.The key intermediates in these syntheses are the diketo sulfones 7a,b, which are prepared by two methods.The reaction of dilithiosulfones 12a,b with γ-valerolactone in tetrahydrofuran in the presence of hexamethylphosphoramide at -78 deg C gives the hydroxy keto sulfones 13a,b in satisfactory yields and the successive oxidation of these compounds with Jones reagent in acetone affords 7a,b in very good yields.On the other hand, the reaction of 12a,b with ethyl levulinate ethylene ketal gives the partially protected diketo sulfones 17a,b, from which 7a,b are obtained by removal of the protecting group.Cleavage of the carbon-sulfur bond in 7a,b, accomplished by aluminum amalgam in aqueous tetrahydrofuran, affords 3a,b which are then cyclized to 1a,b by heating over basic alumina in benzene.