Total Syntheses of a Family of Cadinane Sesquiterpenes

Concise total syntheses of (−)-(1R,6S,7S,10R)-hydroxy­cadinan-3-en-5-one (1), (+)-(1R,5S,6R,7S,10R)-cadinan-3-ene-1,5-diol (2), and (+)-(1R,5S,6R,7S,10R)-cadinan-4­(11)-ene-1,5-diol (3), three cadinane sesquiterpenes sharing identical trans-decalin carbon skeletons yet containing different oxidation states and substitution patterns, are reported. They were prepared from a common trans-decalin intermediate, which was readily prepared on gram scale through an aldol-Henry reaction cascade and oxidation sequence.