From Axial Chirality to Central Chiralities: Pinacol Cyclization of 2,2′-Biaryldicarbaldehyde to trans-9,10-Dihydrophenanthrene-9,10-diol

Two salient features—the stereoselectivity to give only the trans-diol, and the stereospecificity to transmit the axial chirality (in case the starting biphenyl is configurationally stable) onto two stereogenic centers of the product—characterize the pinacol cyclization of 2,2′-biaryldicarbaldehydes (see reaction). The accessibility of trans-9,10-dihydrophenanthrene-9,10-diols provides the new enantiopure C2-symmetric diol 1, which shows potential utility in asymmetric synthesis.