The enantioselective desymmetrizing conjugate hydrosilylation of prochiral differently γ,γ-disubstituted cyclohexadienone derivatives 2 to furnish the corresponding cyclohexenones 4 with a remote chiral all-carbon quaternary center at the γ position is described. Chiral rhodium-bis(oxazolinyl)phenyl complexes 1 were effective catalysts for this transformation. This catalytic system was extended to the asymmetric transformation of spirocarbocyclic cyclohexadienones 5 to give the corresponding products 6 with high enantiomeric ratios.

Rhodium-catalyzed enantioselective desymmetrizing intramolecular hydrosilylation of symmetrically disubstituted hydrosilanes is described. The original axially chiral phenanthroline ligand (S)-BinThro (Binol-derived phenanthroline) was found to work as an effective chiral catalyst for this transformation. A chiral silicon stereogenic center is one of the chiral motifs gaining much attention in asymmetric syntheses and the present protocol provides cyclic five-membered organosilanes incorporating chiral silicon centers with high enantioselectivities (up to 91 % ee). The putative active Rh(I) catalyst takes the form of an N,N,O-tridentate coordination complex, as determined by several complementary experiments.

The enantioselective desymmetrizing conjugate hydrosilylation of prochiral differently γ,γ‐disubstituted cyclohexadienone derivatives 2 to furnish the corresponding cyclohexenones 4 with a remote chiral all‐carbon quaternary center at the γ position is described. Chiral rhodium–bis(oxazolinyl)phenyl complexes 1 were effective catalysts for this transformation. This catalytic system was extended to the asymmetric transformation of spirocarbocyclic cyclohexadienones 5 to give the corresponding products 6 with high enantiomeric ratios.

Asymmetric desymmetrization was demonstrated by means of transition-metal-catalyzed conjugate reduction with hydrosilanes as reductants. Chiral rhodium-bis(oxazolinyl)phenyl complexes [Rh(Phebox-R)] were found to be effective catalysts for conjugate hydrosilylation of differently γ,γ-disubstituted cyclohexadienones to provide the corresponding product with chiral quaternary centers. The mechanistic consideration was also performed by theoretical calculation. These attempts provided information about i) the initial activation of Rh(III) complex into Rh(I) species assisted by hydrosilanes, ii) the complete catalytic cycle, and iii) an explanation of the asymmetric induction and the difference of the structure of cyclohexadienones in enantioselectivity.

An enantioselective conjugate hydrosilylation of prochiral γ,γ‐disubstituted cyclohexadienones furnishes cyclohexenones with a chiral quaternary γ‐carbon atom.