Ruthenium(II)-Catalyzed Regioselective 1,6-Conjugate Addition of Umpolung Aldehydes as Rational Carbanion Equivalents

One of the most efficient and reliable approaches to systematic constructions of C-C bonds involves the conjugate addition of carbon nucleophiles to electron-deficient olefins. Yet, 1,6-conjugate additions of extended conjugated systems largely remain underexplored due to difficulties in controlling regioselectivity. Herein, we report umpolung aldehydes as carbanion equivalents for highly regioselective 1,6-conjugate addition reactions to extended ketones with asymmetric studies. The synergy of ruthenium(II) catalyst and electron-rich, bidentate phosphine ligand is essential for the reactivity, selectivity, and broad substrate scope applicability under mild reaction conditions.