Xumu Zhang

Pd-Catalyzed Asymmetric Hydrogenation of Unprotected Indoles Activated by Brønsted Acids

The first highly enantioselective hydrogenation of simple indoles was developed with a Brønsted acid as an activator to form the iminium intermediate in situ, which was hydrogenated using Pd(OCOCF(3))(2)/(R)-H8-BINAP catalyst system with up to 96% ee. The present method provides an efficient route to enantioenriched 2-substituted and 2,3-disubstituted indolines.

Highly Enantioselective Hydrogenation of Simple Ketones Catalyzed by a Rh - PennPhos Complex**

Even alkyl methyl ketones undergo asymmetric hydrogenation with high enantioselectivity when a rhodium complex of the conformationally rigid chiral ligand 1 (Me-PennPhos; R=CH3 ) is used as the catalyst. Basic additives such as 2,6-lutidine contribute to the achievement of high enantiomeric excesses.

Spiro[4,4]‐1,6‐nonadiene‐Based Phosphine–Oxazoline Ligands for Iridium‐Catalyzed Enantioselective Hydrogenation of Ketimines

From imines to amines through catalysis by Ir(I) complexes of a new type of P,N ligand (see scheme): This reaction affords the corresponding optically active amines with up to 98 % ee and has also been used with perfect stereoselectivity in the asymmetric synthesis of sertraline (1), an important antidepressant chiral drug.

Development of New Chiral P,N Ligands and Their Application in the Cu-Catalyzed Enantioselective Conjugate Addition of Diethylzinc to Enones.

High enantioselectivity (up to 98 % ee) has been achieved for the conjugate addition of diethylzinc to acyclic enones utilizing Cu(I) complexes of the novel chiral P,N ligands 1. The high enantioselectivities are best achieved using [Cu(OTf)](2) small middle dotC(6)H(6) as the copper catalyst precursor in nonpolar solvents such as toluene or Cl(CH(2))(2)Cl. R=H, CH(3); Tf=F(3)CSO(2).

Enantioselective Hydrogenation of N-H Imines

N-H ketoimines 3a-3v are readily prepared in high yield via organometallic addition to nitriles and isolated as corresponding bench-stable hydrochloride salts. Homogeneous asymmetric hydrogenation of unprotected N-H ketoimines 3a-3v using Ir-(S,S)-f-binaphane as catalyst provides chiral amines 4a-4v in 90-95% yield with enantioselectivities up to 95% ee.

Rhodium-Catalyzed Direct Oxidative Carbonylation of Aromatic C−H Bond with CO and Alcohols

A general protocol for the rhodium-catalyzed oxidative carbonylation of arenes to form esters has been developed. A broad substrate scope has been demonstrated allowing carbonylation of electron-rich, electron-poor, and heterocyclic arenes, and the reaction shows wide functional group tolerance and excellent regioselectivities. Up to 96% yield of ortho-substituted aryl or heteroaryl carboxylic esters were obtained with this methodology. The possible mechanism for the rhodium-catalyzed oxidative carbonylation reaction was proposed in this article. Studies show that Oxone play an important role in the transformation.

Highly Enantioselective Cycloisomerization of Enynes Catalyzed by Rhodium for the Preparation of Functionalized Lactams

The rising demand for chiral raw materials, intermediates, and active ingredients in pharmaceuticals, agrochemicals, food additives, and fragrances provides the impetus for rapid developments in chiral technology.[1] It remains a huge challenge for organic chemists to develop highly enantioselective reactions for the preparation of enantiomerically pure compounds in a cost-effective manner. Lactams are a versatile motif in organic chemistry and when functionalized, lactams often either show biological activity themselves, or are important building blocks for biologically active molecules such as (þ)-a-allokainic acid, (þ)-a-kainic acid,[2] acromelic

Iridium−Monodentate Phosphoramidite-Catalyzed Asymmetric Hydrogenation of Substituted Benzophenone N−H Imines

Homogeneous asymmetric hydrogenation of unprotected benzophenone N-H imines 1a-r using Ir-(S)-N-benzyl-N-methyl-MonoPhos as a catalyst provides chiral amines 2a-r in 80-96% yield with enantioselectivities up to 98% ee (18 examples) for ortho-substituted substrates.

An unexpected phosphine-catalyzed [3 + 2] annulation. Synthesis of highly functionalized cyclopentenes.

An unexpected phosphine-catalyzed [3 + 2] annulation from electron-deficient allenes and substituted alkylidenemalononitriles was realized in which the allylic moiety of the substituted alkylidenemalononitriles served as the three carbon unit of the cyclopentenes instead of the electron-deficient allenes.

Synthesis of (1,1′)-2,6-bis[1-(diphenylphosphino)ethyl]pyridine and its application in asymmetric transfer hydrogenation

Abstract A C 2 symmetric tridentate ligand, (1R, 1R′) 2,6-Bis[1-(diphenylphosphino)ethyl]pyridine, has been synthesized in enantiomerically pure form. A practical method to synthesize a variety of chiral pyridyl diols is reported. Asymmetric transfer hydrogenation is achieved using the tridentate ligand.