Enantioselective installation of adjacent tertiary benzylic stereocentres using lithiation-borylation-protodeboronation methodology. Application to the synthesis of bifluranol and fluorohexestrol.

ABSTRACT: 1,2-Diaryl ethanes bearing 1,2-stereogenic centres show interesting biological activity but their stereocontrolled synthesis has not been reported forcing a reliance of methods involving diastereomer and enantiomer separation. We have found that this class of molecules can be prepared with very high stereocontrol using lithiation-borylation methodology. The reaction of an enantioenriched benzylic lithiated carbamate with an enantioenriched benzylic secondary pinacol boronic ester gave a tertiary boronic ester with complete diastereo- and enantiocontrol. It was essential to use MgBr₂/MeOH after formation of the boronate complex, both to promote the 1,2-migration and to trap any lithiated carbamate/benzylic anion that formed from fragmentation of the ate complex, anions that would

SUBMITTER: Roesner S 

PROVIDER: S-EPMC5707455 | biostudies-literature | 2015 Jul

REPOSITORIES: biostudies-literature