Stepwise approach for sterically hindered Csp3–Csp3 bond formation by dehydrogenative O-alkylation and Lewis acid-catalyzed [1,3]-rearrangement towards the arylalkylcyclopentane skeleton of sesquiterpenes

Abstract

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.