ALICYCLIC TERPENOIDS FROM CYCLOCITRAL PHENYL SULFIDES. I. ACID-CATALYZED CYCLIZATION OF GERANYL PHENYL SULFIDES TO CYCLOCITRAL DERIVATIVES. A SYNTHESIS OF α- AND β-IONONES

Abstract
Cyclocitryl phenyl sulfides (IIa and IIIa) and sulfones (lIb and IIIb) were efficiently prepared by acid-catalyzed cyclization of geranyl phenyl sulfide (Ia) and sulfone (Ib). The sulfones (IIb and IIIb) could be converted into α- and β-ionones. The cyclization of citral diphenylthioacetal (ic) afforded the tricyclic compound (Vl), The detailed cyclization conditions are discussed.