Cobalt-Catalyzed Effective Access to Quinoxalines with Insights in Annulation of Terminal Alkynes and -Phenylenediamines.

A novel methodology for the annulation of terminal alkynes and -phenylenediamines by using a combination of a cobalt catalyst and oxygen as a terminal oxidant is reported. This method shows wide substrate scope and good functional group tolerance and provides a wide range of quinoxalines in good to high yields. The method is demonstrated by its gram-scale and broad potential applications.

Pd-Catalyzed Intramolecular Chemoselective C(sp2)-H and C(sp3)-H Activation of N-Alkyl- N-arylanthranilic Acids.

A controllable palladium-catalyzed intramolecular C-H activation of N-alkyl- N-arylanthranilic acids has been developed. The methodology allows selective synthesis of 1,2-dihydro-(4 H)-3,1-benzoxazin-4-ones and carbazoles from the same starting materials and palladium catalyst. The selectivity is controlled by the oxidant.

Discovery of a Bioactive Inhibitor with a New Scaffold for Cystathionine γ-Lyase.

We identify three submicromolar inhibitors with new chemical scaffolds for cystathionine γ-lyase (CSE) by a tandem-well-based high-throughput assay. NSC4056, the most potent inhibitor with an IC of 0.6 μM, which is also known as aurintricarboxylic acid, selectively binds to Arg and Tyr residues of CSE active site and preferably inhibits the CSE activity in cells rather than cystathionine β-synthase (CBS), the other HS-generating enzyme.

Enantioselective Synthesis of 3-Alkynyl-3-hydroxyindolin-2-ones by Copper-Catalyzed Asymmetric Addition of Terminal Alkynes to Isatins.

A highly efficient copper-catalyzed asymmetric addition of terminal alkynes to isatins has been developed. In the presence of a catalytic amount of copper iodide and a chiral phosphine ligand, the reaction gave the corresponding chiral 3-alkynyl-3-hydroxyindolin-2-ones in high yields with high enantioselectivity. This methodology has a broad substrate scope, and the synthetic utility of the present protocol was further demonstrated by the transformation of chiral alkynylation products.

Copper-catalyzed annulation of heteroaromatic β-halo-α,β-unsaturated carboxylic acids with alkynes for the synthesis of indolo[2,3-c]pyrane-1-ones and thieno[2,3-c]pyrane-7-ones.

The annulation of heteroaromatic β-halo-α,β-unsaturated carboxylic acids with alkynes proceeds efficiently in the presence of Cu(OAc)2·H2O as a catalyst to afford the corresponding indolo[2,3-c]pyrane-1-ones and thieno[2,3-c]pyrane-7-ones in moderate to good yields. This strategy offers a simple and efficient route for the synthesis of indolo[2,3-c]pyrane-1-ones and thieno[2,3-c]pyrane-7-ones with good tolerance to a variety of functional groups from easily available heteroaromatic β-halo-α,β-unsaturated carboxylic acids.

Synthesis of isocoumarin derivatives by copper-catalyzed addition of o-halobenzoic acids to active internal alkynes.

The addition of o-halobenzoic acids to active internal alkynes proceeds efficiently in the presence of CuCl(2) as a catalyst to give the corresponding isocoumarin derivatives in moderate to good yields. This strategy offers a simple, efficient route to synthesis of the isocoumarin derivatives.

Chiral silver amides as effective catalysts for enantioselective [3+2] cycloaddition reactions.

Asymmetric [3+2] cycloaddition of α-aminoester Schiff bases with substituted olefins is one of the most efficient methods for the preparation of chiral pyrrolidine derivatives in optically pure form. In spite of its potential utility, applicable substrates for this method have been limited to Schiff bases that bear relatively acidic α-hydrogen atoms. Here we report a chiral silver amide complex for asymmetric [3+2] cycloaddition reactions.

Chiral silver amide-catalyzed enantioselective [3 + 2] cycloaddition of alpha-aminophosphonates with olefins.

The first catalytic asymmetric [3 + 2] cycloadditions of Schiff bases of alpha-aminophosphonates with olefins have been developed. Chiral silver amide complexes bearing (R)-DTBM-SEGPHOS worked well as catalysts for the first time, and proline phosphonic analogues were obtained in high yields with excellent exo- and enantioselectivities.

Rhodium-catalyzed asymmetric hydroalkoxylation and hydrosulfenylation of diphenylphosphinylallenes.

The rhodium-catalyzed intermolecular asymmetric hydroalkoxylation and hydrosulfenylation of diphenylphosphinylallenes gave chiral allylic phosphine oxides substituted with vinyl ether and thioether moieties in high yields with high enantioselectivities.

Rhodium-catalyzed asymmetric ring-opening alkynylation of azabenzonorbornadienes.

Asymmetric ring-opening alkynylation of meso-azabenzonorbornadienes with (triisopropylsilyl)acetylene giving 2-alkynyl-1-aminodihydronaphthalenes took place in high yields with high enantioselectivity in the presence of a rhodium/(R)-DTBM-segphos catalyst.

Rhodium-catalyzed asymmetric addition of terminal alkynes to diarylphosphinylallenes.

The presence of an acid was found to be essential in the rhodium-catalyzed asymmetric addition of terminal alkynes to diarylphosphinylallenes giving exo-enynes in high yields with high regio- and enantioselectivity. The stereochemical outcome is determined at the protonolysis of the pi-allylrhodium(I) intermediate involved in the catalytic cycle.

Rhodium-catalyzed asymmetric hydrogenation of functionalized olefins using monodentate spiro phosphoramidite ligands.

Novel chiral monodentate phosphorus ligands, SIPHOS, were conveniently synthesized from 1,1'-spirobiindane-7,7'-diol. The Rh complexes of SIPHOS can catalyze the hydrogenation of alpha-dehydroamino esters in mild conditions, providing alpha-amino acid derivatives in up to 99% ee. Enamides and beta-dehydroamino esters can also be hydrogenated in good to excellent enantioselectivities (up to 99% and 94% ee, respectively).