Tryptophan/copper-catalyzed aromatization reaction of chiral cyclohexanones to phenols

Abstract

By merging organocatalysis with copper catalysis, a highly efficient stereospecific approach for the synthesis of chiral phenols from cyclohexanones has been developed for the first time. The aromatization reaction proceeds through the in situ formation of enone intermediates and further subsequent bromination/dehydrobromination reactions. And a series of functionalized phenol derivatives are obtained in good yields (up to 89%) and good to excellent enantioselectivities (up to 99% ee).

Multifunctionalization of Unactivated Cyclic Ketones via Synergistic Catalysis of Copper and Diarylamine: Access to Cyclic α-Enaminone

“…Later, the transformation was found to proceed efficiently with a variety of aryl groups at the C3 position, including phenyl, naphthyl, thienyl, and various substituted phenyl groups ( 3ma – 3sa ). The cyclohexanone could also undergo the desired reaction pathway to offer α-enaminone 3ta , albeit in a low yield of 31%, probably due to the overoxidation of the formed α-enaminone . When 3,3- or 4,4-dimethylcyclohexanone were empolyed as the substrates, 3ua and 3va were obtained in acceptable yields.…”