Ruthenium-catalyzed deformylative C–C activation and carbene insertion towards diversity-oriented synthesis of unsymmetrical biaryldiols and heterobiaryl amino alcohols

While 1,1-biaryl diols and amino alcohols are privileged scaffolds, their streamlined catalytic synthesis with unsymmetrical substitution patterns remains a daunting challenge. Herein, we describe the first ruthenium(II)-catalyzed synthesis of un-symmetrical 1,1-biaryl-2,2-diols via a deformylative coupling of ortho-hydroxy aromatic aldehydes with diverse cyclic di-azo compounds. The protocol is operationally simple, scalable, and involves intriguing C–C bond activation and carbene insertion cascade to produce a range of diversely functionalized biaryl diols in very high to excellent yields and regioselectivity. The methodology is also suitable to access heterobiaryl amino alcohols bearing indole motif, applicable in challenging two-fold C–C activation leading to valuable tetrahydroxy bis-biaryls, and retains efficacy in the site-selective modification of pharmaceutical agents. DFT studies have also been conducted to illustrate the intricacy of this catalytic cycle.