An organic reductant, in particular an organo silicon reductant suitable for activating supported catalysts of the type MO.sub.nE.sub.m, wherein E is S and/or Se, in particular MO.sub.n, wherein M is W, Mo or Re, is described as well as its use in metathesis reactions. The reduced catalysts are able to metathesize olefins at low temperatures and are therefore also suitable for metathesis of functionalized olefins.

Disclosed are N-heterocyclic carbene (NHC) and 4-pyridinol-derived pincer ligands and metal complexes containing these ligands. These compounds can be used to photocatalyticaly reduce CO.sub.2 to CO.

The subject invention pertains to a method of halogenating phenols, yielding a range of halogenated phenols with enantiomeric ratio of up to 99.5:0.5. In certain embodiments, the subject invention pertains to a method of asymmetric halogenation of bisphenol, yielding a range of chiral bisphenol ligands. The novel chiral bisphenols are potent privileged catalyst cores that can be applied to the preparation of ligands for various catalytic asymmetric reactions. The catalyst library can easily be accessed because late-stage modification of the scaffold can readily be executed through cross-coupling of the halogen handles on the bisphenols.

The subject invention pertains to a method of halogenating phenols, yielding a range of halogenated phenols with enantiomeric ratio of up to 99.5:0.5. In certain embodiments, the subject invention pertains to a method of asymmetric halogenation of bisphenol, yielding a range of chiral bisphenol ligands. The novel chiral bisphenols are potent privileged catalyst cores that can be applied to the preparation of ligands for various catalytic asymmetric reactions. The catalyst library can easily be accessed because late-stage modification of the scaffold can readily be executed through cross-coupling of the halogen handles on the bisphenols.

The subject invention pertains to a method of halogenating phenols, yielding a range of halogenated phenols with enantiomeric ratio of up to 99.5:0.5. In certain embodiments, the subject invention pertains to a method of asymmetric halogenation of bisphenol, yielding a range of chiral bisphenol ligands. The novel chiral bisphenols are potent privileged catalyst cores that can be applied to the preparation of ligands for various catalytic asymmetric reactions. The catalyst library can easily be accessed because late-stage modification of the scaffold can readily be executed through cross-coupling of the halogen handles on the bisphenols.

Disclosed are N-heterocyclic carbene (NHC) and 4-pyridinol-derived pincer ligands and metal complexes containing these ligands. These compounds can be used to photocatalyticaly reduce CO.sub.2 to CO.

The present invention discloses a method for preparing optically active carbonyl compound, comprising the following steps: under the catalysis of chiral amine salt and transition metal catalysts, with hydrogen and catalytic amount of dihydropyridine compound as hydrogen source, use , -unsaturated aldehydes or , -unsaturated troponoid compounds to conduct asymmetric catalytic reaction to obtain the optically active carbonyl compound. This method comes in moderate reaction condition, simple operation, and catalytic amount of dihydropyridine compounds usage, the target product is easy to be separated and purified from the reaction system, and the metal catalyst can be recycled, it is economical.