2-(2-Mercaptoethylthio)cyclopenta-1,3-dienes are thermally generated in situ from cyclopent-2-en-1-one dithioacetals under neutral conditions and intercepted with dienophiles ultimately to give norbornan-2-one dithioacetals.
Direct synthesis of 2-norbornanone dithioacetals from 2-cyclopentenone dithioacetals and dienophiles. Synthetic application of thermal interconversion between cyclic dithioacetals and the ring-opened vinyl sulfide forms
via the in situ generated 1,3-cyclopentadien-2-yl sulfide tautomers, in acetonitrile at 120°C to give 2-norbornanone dithioacetals in 79–93% yields. This transformation represents, to our knowledge, the first syntheticapplication of thermal interconversion between cyclic dithioacetals and the ring-opened vinyl sulfide forms.