Stepwise approach for sterically hindered C sp3 –C sp3 bond formation by dehydrogenative O -alkylation and Lewis acid-catalyzed [1,3]-rearrangement towards the arylalkylcyclopentane skeleton of sesquiterpenes

A stepwise dehydrogenative cross-coupling method was developed for the formation of sterically hindered C sp3 –C sp3 bonds. Intramolecular dehydrogenative O -alkylation of a β-ketoester by 2,3-dichloro-5,6-dicyano- p -benzoquinone to form an oxolane followed by Lewis acid-catalyzed [1,3]-rearrangement furnished the sesquiterpene arylmethylcyclopentane skeleton. The formal syntheses of herbertane-type β-herbertenol, cuparane-type enokipodins A and B were also achieved.