Cooperative Diarylborinic Acid/Chloride-Catalyzed Formal Si Reaction of -4-Hydroxymethyl-1,2-Cyclopentene Oxides.

A catalytic formal Si reaction was designed to achieve stereoretentive products for -4-hydroxymethyl-1,2-cyclopentene oxides by using diarylborinic acid as a dual role catalyst and chloride as a catalytic transient nucleophile through a double-displacement mechanism. This reaction offers the advantages of a low catalyst loading of 0.1 mol % and wide substrate scope, even including -substituents.

Diarylborinic Acid-Catalyzed Ring Opening of -4-Hydroxymethyl-1,2-Cyclopentene Oxides: Synthesis of 1,2,4-Trisubstituted Cyclopentanes.

A diarylborinic acid-catalyzed ring opening of -4-hydroxymethyl-1,2-cyclopentene oxides was developed with -nucleophiles including anilines, benzotriazole, and alkylamines, as well as -nucleophiles, affording 1,2,4-trisubstituted cyclopentane compounds containing a quaternary carbon center. The mechanism study indicated that the "half-cage" structure formed by the epoxide substrate and the catalyst prevents the nucleophiles from attacking the inner side of the "half-cage", resulting in the desired ring-opening product.

Regioselective hydroesterification of alkenes and alkenylphenols utilizing CO and hydrosilane.

As an important and attractive C1 building block, the diversified exploitation of CO in chemical transformations possesses significant research and application value. Herein, an effective palladium-catalyzed intermolecular hydroesterification of a wide range of alkenes with CO and PMHS is described, successfully generating diverse esters with up to 98% yield and up to 100% linear-selectivity. In addition, the palladium-catalyzed intramolecular hydroesterification of alkenylphenols with CO and PMHS is also developed to construct a variety of 3-substituted-benzofuran-2(3)-ones with up to 89% yield under mild conditions.

Electrocatalytic NAD reduction hydrogen atom-coupled electron transfer.

Nicotinamide adenine dinucleotide cofactor (NAD(P)H) is regarded as an important energy carrier and charge transfer mediator. Enzyme-catalyzed NADPH production in natural photosynthesis proceeds a hydride transfer mechanism. Selective and effective regeneration of NAD(P)H from its oxidized form by artificial catalysts remains challenging due to the formation of byproducts.

Direct synthesis of -methyl benzaldehyde from acetaldehyde via an organic amine-catalyzed dehydrogenation mechanism.

-Methyl benzaldehyde (-MBA) is a class of key chemical intermediates of pharmaceuticals. Conventional industrial processes for -MBA production involve the consecutive photochlorination, amination, and acid hydrolysis of petroleum-derived -xylene, while producing vast pollutants and waste water. Herein, we report a direct, green route for selective synthesis of -MBA from acetaldehyde using a diphenyl prolinol trimethylsilyl ether catalyst.

Controllable stereoinversion in DNA-catalyzed olefin cyclopropanation cofactor modification.

The assembly of DNA with metal-complex cofactors can form promising biocatalysts for asymmetric reactions, although catalytic performance is typically limited by low enantioselectivities and stereo-control remains a challenge. Here, we engineer G-quadruplex-based DNA biocatalysts for an asymmetric cyclopropanation reaction, achieving enantiomeric excess (ee) values of up to +91% with controllable stereoinversion, where the enantioselectivity switches to -72% ee through modification of the Fe-porphyrin cofactor. Complementary circular dichroism, nuclear magnetic resonance, and fluorescence titration experiments show that the porphyrin ligand of the cofactor participates in the regulation of the catalytic enantioselectivity a synergetic effect with DNA residues at the active site.

Water-initiated hydrocarboxylation of terminal alkynes with CO and hydrosilane.

This work discloses a Cu(ii)-Ni(ii) catalyzed tandem hydrocarboxylation of alkynes with polysilylformate formed from CO2 and polymethylhydrosiloxane that affords α,β-unsaturated carboxylic acids with up to 93% yield. Mechanistic studies indicate that polysilylformate functions as a source of CO and polysilanol. Besides, a catalytic amount of water is found to be critical to the reaction, which hydrolyzes polysilylformate to formic acid that induces the formation of Ni-H active species, thereby initiating the catalytic cycle.

Tandem one-pot CO reduction by PMHS and silyloxycarbonylation of aryl/vinyl halides to access carboxylic acids.

The present study discloses the synthesis of aryl/vinyl carboxylic acids from Csp2-bound halides (Cl, Br, I) in a carbonylative path by using silyl formate (from CO2 and hydrosilane) as an instant CO-surrogate. Hydrosilane provides hydride for reduction and its oxidation product silanol serves as a coupling partner. Mono-, di-, and tri-carboxylic acids were obtained from the corresponding aryl/vinyl halides.

Enantioselective sulfoxidation reaction catalyzed by a G-quadruplex DNA metalloenzyme.

Enantioselective sulfoxidation reaction is achieved for the first time by a DNA metalloenzyme assembled with the human telomeric G-quadruplex DNA and Cu(ii)-4,4'-bimethyl-2,2'-bipyridine complex, and the mixed G-quadruplex architectures are responsible for the catalytic enantioselectivity and activity.

A highly enantioselective thiolation of sulfonyl indoles to access 3-sec-sulfur-substituted indoles in water.

A highly enantioselective approach for the synthesis of 3-alkyl- indole or indoline derivatives with a functional thiol group is presented. The chemistry is based on the asymmetric 1,4-addition of thiol to vinylogous imine intermediates, which are generated in situ from sulfonylindoles. The broad substrate transformation proceeds with high yields (up to 96%) and enantioselectivity (up to 98% ee) in a water-compatible system.

A remarkable difference in CO2 hydrogenation to methanol on Pd nanoparticles supported inside and outside of carbon nanotubes.

An obvious difference was found in CO2 hydrogenation to methanol on Pd nanoparticles (NPs) supported inside and outside of carbon nanotubes (CNTs). The turnover frequency of methanol synthesis on the Pd NPs supported inside of CNTs was 3.7 times those supported outside of CNTs.

Unprecedentedly high formic acid dehydrogenation activity on an iridium complex with an N,N'-diimine ligand in water.

Hydrogen production from the dehydrogenation of formic acid (FA) is promising. Most of the current catalysts for FA dehydrogenation are effective only in the presence of bases or additives. We report here newly developed iridium complexes containing conjugated N,N'-diimine ligands for FA dehydrogenation in water without the addition of bases or additives.

The synthesis of chiral isotetronic acids with amphiphilic imidazole/pyrrolidine catalysts assembled in oil-in-water emulsion droplets.

Drop it! A highly enantioselective catalytic cascade reaction of α-ketoacids and aldehydes is achieved using the title catalyst and water as the solvent. Fluorescence imaging shows that the catalyst is mainly distributed on the surface of emulsion droplets. Optically active isotetronic acids can be obtained with this method and the emulsion droplets are responsible for the high reactivity and enantioselectivity.

Enantioselective Friedel-Crafts reactions in water catalyzed by a human telomeric G-quadruplex DNA metalloenzyme.

A human telomeric G-quadruplex (G4DNA) metalloenzyme, assembled with G4DNA and Cu(2+) ions, can catalyze the enantioselective Friedel-Crafts (F-C) reaction in water with good enantioselectivity (up to 75% ee). Furthermore, we found that the absolute configuration and the enantioselectivity of the product largely depend on the conformation and the sequence of G4DNA.

Chiral sulfur compounds studied by Raman optical activity: tert-butanesulfinamide and its precursor tert-butyl tert-butanethiosulfinate.

Two chiral sulfur compounds, tert-butyl tert-butanethiosulfinate (1) and tert-butanesulfinamide (2), with inversion of configuration, have been studied by Raman optical activity (ROA) and electronic circular dichroism combined with density functional theory calculation. With the S-S linkage in 1, the couplings between the two tertiary carbon atoms often generate large ROA signals, whereas the tertiary carbon atom itself generally makes a large contribution to ROA signals in 2 for similar vibrational modes. The conformational dependence of ROA parameters provides probing conformation around the S-S bond from a new perspective.

Highly enantioselective iridium-catalyzed hydrogenation of 2-benzylquinolines and 2-functionalized and 2,3-disubstituted quinolines.

The enantioselective hydrogenation of 2-benzylquinolines and 2-functionalized and 2,3-disubstituted quinolines was developed by using the [Ir(COD)Cl](2)/bisphosphine/I(2) system with up to 96% ee. Moreover, mechanistic studies revealed the hydrogenation mechanism of quinoline involves a 1,4-hydride addition, isomerization, and 1,2-hydride addition, and the catalytic active species may be a Ir(III) complex with chloride and iodide.

Highly enantioselective Pd-catalyzed asymmetric hydrogenation of activated imines.

Pd/bisphosphines complexes are highly effective catalysts for asymmetric hydrogenation of activated imines in trifluoroethanol. The asymmetric hydrogenation of N-diphenylphosphinyl ketimines 3 with Pd(CF3CO2)/(S)-SegPhos indicated 87-99% ee, and N-tosylimines 5 could gave 88-97% ee with Pd(CF3CO2)/(S)-SynPhos as a catalyst. Cyclic N-sulfonylimines 7 and 11 were hydrogenated to afford the useful chiral sultam derivatives in 79-93% ee, which are important organic synthetic intermediates and structural units of agricultural and pharmaceutical agents.

Palladium-catalyzed asymmetric hydrogenation of functionalized ketones.

[reaction: see text]. A novel catalytic system for asymmetric hydrogenation of functionalized ketones has been developed using a Pd/bisphosphine complex as the catalyst in 2,2,2-trifluoroethanol. The reaction exhibits high enantioselectivity, and up to 92.

Highly enantioselective iridium-catalyzed hydrogenation of heteroaromatic compounds, quinolines.

The highly enantioselective hydrogenation of quinoline derivatives is developed using [Ir(COD)Cl]2/(R)-MeO-Biphep/I2 system, and this methodology has been applied to the asymmetric synthesis of three naturally occurring alkaloids angustureine, galipinine, and cuspareine. This method provided an efficient access to a variety of optically active tetrahydroquinolines with up to 96% ee.