Month: October 2022

Sekine, Keisuke; Akaishi, Dai; Konagaya, Kakeru; Ito, Shigekazu published the artcile< Copper-Catalyzed Enantioselective Hydrosilylation of gem-Difluorocyclopropenes Leading to a Stereochemical Study of the Silylated gem-Difluorocyclopropanes>, Name: (S)-(-)-2,2′-Bis(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl, the main research area is cyclopropene difluoro asym hydrosilylation silylboronate preparation chiral arylcyclopropane; copper chiral diphosphine monophosphine catalyst asym hydrosilylation difluorocyclopropene; asymmetric synthesis; copper catalysis; cyclopropanes; fluorine; racemization.

1-Aryl-2,2-difluorocyclopropenes ArC3HF2 undergo asym. hydrosilylation with pinBSiPhMe2 catalyzed by copper(I) complexes with mono- and bidentate chiral phosphines, affording trans-silylcyclopropanes ArCH(CF2)CHSiPhMe2 with up to 95% ee, which upon desilylation gave chiral 2-aryl-1,1-difluorocyclopropanes. Optically active cyclopropanes have been widely investigated especially from the views of pharmaceutical and agrochem. industries, and substituting one of the methylenes with the difluoromethylene unit should be promising for developing novel biol. relevant compounds and functional materials. In this paper, the copper-catalyzed enantioselective hydrosilylation of gem-difluorocyclopropenes to provide the corresponding chiral gem-difluorocyclopropanes is presented. The use of copper(I) chloride, chiral ligands including bidentate BINAPs and monodentate phosphoramidites, and silylborane Me2PhSi-Bpin accompanying sodium tert-butoxide in methanol was appropriate for the enantioselective hydrosilylation of the strained C:C double bond, and the resultant chiral difluorinated three-membered ring was unambiguously characterized. Subsequent activation of the silyl groups in enantio-enriched gem-difluorocyclopropanes showed substantial reduction of the enantiopurity, indicating cleavage of the distal C-C bond leading to the transient acyclic intermediates.

Chemistry – A European Journal published new progress about Chiral ligands Role: CAT (Catalyst Use), USES (Uses) (chiral phosphines). 139139-93-8 belongs to class chiral-phosphine-ligands, and the molecular formula is C44H40P2, Name: (S)-(-)-2,2′-Bis(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate

Felix, Ryan J.; Weber, Dieter; Gutierrez, Osvaldo; Tantillo, Dean J.; Gagne, Michel R. published the artcile< A gold-catalysed enantioselective Cope rearrangement of achiral 1,5-dienes>, Computed Properties of 325168-88-5, the main research area is gold catalysis enantioselective cope rearrangement achiral dienes.

Since the discovery of the Cope rearrangement in the 1940s, no asym. variant of the rearrangement of achiral 1,5-dienes has emerged, despite the successes that have been achieved with its heteroatom variants (Claisen, aza-Cope, and so on). This article reports the first example of an enantioselective Cope reaction that starts from an achiral diene. The new gold(I) catalyst derived from double Cl–abstraction of ((S)-3,5-xylyl-PHANEPHOS(AuCl)2), has been developed for the sigmatropic rearrangement of alkenyl-methylenecyclopropanes. The reaction proceeds at low temperature and the synthetically useful vinylcyclopropane products are obtained in high yield and enantioselectivity. D. functional theory calculations predict that: (1) the reaction proceeds via a cyclic carbenium ion intermediate, (2) the relief of strain in the methylenecyclopropane moiety provides the thermodn. driving force for the rearrangement and (3) metal complexation of the transition-state structure lowers the rearrangement barriers.

Nature Chemistry published new progress about [3,3]-Sigmatropic rearrangement. 325168-88-5 belongs to class chiral-phosphine-ligands, and the molecular formula is C48H50P2, Computed Properties of 325168-88-5.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate

Tanaka, Ken; Sagae, Hiromi; Toyoda, Kazuki; Hirano, Masao published the artcile< Enantioselective synthesis of planar-chiral metacyclophanes through cationic Rh(I)/modified-BINAP-catalyzed inter- and intramolecular alkyne cyclotrimerizations>, Safety of (R)-2,2′-Bis(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl, the main research area is enantioselective synthesis chiral metacyclophane rhodium BINAP catalyst alkyne cyclotrimerization.

We have achieved the first catalytic enantioselective synthesis of planar-chiral metacyclophanes by means of cationic Rh(I)/(S)-xyl-H8-BINAP or (R)-H8-BINAP complex-catalyzed inter- and intramol. alkyne cyclotrimerizations. This highly enantioselective catalysis represents a versatile new method for the preparation of planar-chiral metacyclophanes.

Tetrahedron published new progress about Cyclotrimerization. 139139-86-9 belongs to class chiral-phosphine-ligands, and the molecular formula is C44H40P2, Safety of (R)-2,2′-Bis(diphenylphosphino)-5,5′,6,6′,7,7′,8,8′-octahydro-1,1′-binaphthyl.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate

Goulioukina, Nataliya S.; Shergold, Ilya A.; Rybakov, Victor B.; Beletskaya, Irina P. published the artcile< One-Pot Two-Step Synthesis of Optically Active α-Amino Phosphonates by Palladium-Catalyzed Hydrogenation/Hydrogenolysis of α-Hydrazono Phosphonates>, Category: chiral-phosphine-ligands, the main research area is chiral hydrazono amino phosphonate palladium catalyzed enantioselective hydrogenation; crystal structure chiral hydrazono amino phosphonate; mol structure chiral hydrazono amino phosphonate; amino phosphonate chiral preparation optical activity.

An efficient and convenient 1-pot procedure for the stereoselective catalytic synthesis of ring-substituted [amino(phenyl)methyl]phosphonates was developed. The enantioselective hydrogenation of easily available diisopropyl (Z)-[aryl(phenylhydrazono)methyl]phosphonates using Pd(II) acetate as a precatalyst, (R)-2,2′-bis(diphenylphosphino)-5,5′-dichloro-6,6′-dimethoxy-1,1′-biphenyl [(R)-Cl-MeO-BIPHEP] as a ligand, and (1S)-(+)-10-camphorsulfonic acid as an activator in a mixture of 2,2,2-trifluoroethanol and CH2Cl2 at ambient temperature gave corresponding [aryl(2-phenylhydrazino)methyl]phosphonates. The subsequent cleavage of the N-N bond was accomplished with H2 after the addition of Pd on C and MeOH into crude reaction mixture to afford the optically active [amino(aryl)methyl]phosphonates. The method is operationally simple and provides an appreciable enantioselectivity up to 98% ee.

Advanced Synthesis & Catalysis published new progress about Crystal structure. 139139-93-8 belongs to class chiral-phosphine-ligands, and the molecular formula is C44H40P2, Category: chiral-phosphine-ligands.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate

Li, Min; Li, Bin; Xia, Hong-Feng; Ye, Danru; Wu, Jing; Shi, Yifeng published the artcile< Mesoporous silica KIT-6 supported superparamagnetic CuFe2O4 nanoparticles for catalytic asymmetric hydrosilylation of ketones in air>, Product Details of C44H40P2, the main research area is silica copper iron oxide nanoparticle catalyst ketone asym hydrosilylation.

A diverse range of prochiral ketones were reduced in air with high yields and good-to-excellent enantioselectivities (up to 97% ee) in the presence of a heterogeneous catalyst system, which was in situ formed from catalytic amounts of superparamagnetic CuFe2O4 nanoparticles supported on mesoporous silica KIT-6 and non-racemic dipyridylphosphine ligand, the stoichiometric hydride donor polymethylhydrosiloxane (PMHS) as well as certain amounts of additives. The magnetically separable catalysts could be efficiently reused 4 times without apparent loss of both the activity and enantioselectivity.

Green Chemistry published new progress about Catalyst supports. 139139-93-8 belongs to class chiral-phosphine-ligands, and the molecular formula is C44H40P2, Product Details of C44H40P2.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate

Cao, Simin; Li, Haoyang; Liu, Yangyi; Zhang, Mengjie; Wang, Mengyu; Zhou, Zhongneng; Chen, Jinquan; Zhang, Sanjun; Xu, Jianhua; Knutson, Jay R. published the artcile< Femtosecond Fluorescence Spectra of NADH in Solution: Ultrafast Solvation Dynamics>, Recommanded Product: ((2R,3S,4R,5R)-5-(6-Aminopurin-9-yl)-3,4-dihydroxy-oxolan-2-yl)methoxy-((((2R,3S,4R,5R)-5-(3-carbamoyl-4H-pyridin-1-yl)-3,4-dihydroxy-oxolan-2-yl)methoxy)hydroxyphosphoryl)oxyphosphinic acid disodium salt, the main research area is femtosecond fluorescence spectra NADH Solution ultrafast solvation dynamics.

The ultrafast solvation dynamics of reduced NAD (NADH) free in solution has been investigated, using both a femtosecond upconversion spectrophotofluorometer and a picosecond time-correlated single-photon counting (TCSPC) apparatus The familiar time constant of solvent relaxation originating in “”bulk water”” was found to be ∼1.4 ps, revealing ultrafast solvent reorientation upon excitation. We also found a slower spectral relaxation process with an apparent time of 27 ps, suggesting there could either be dissociable “”biol. water”” hydration sites on the surface of NADH or internal dielec. rearrangements of the flexible solvated mol. on that timescale. In contrast, the femtosecond fluorescence anisotropy measurement revealed that rotational diffusion happened on two different timescales (3.6 ps (local) and 141 ps (tumbling)); thus, any dielec. rearrangement scenario for the 27 ps relaxation must occur without significant chromophore oscillator rotation. The coexistence of quasi-static self quenching (QSSQ) with the slower relaxation is also discussed.

Journal of Physical Chemistry B published new progress about Fluorescence. 606-68-8 belongs to class chiral-phosphine-ligands, and the molecular formula is C21H27N7Na2O14P2, Recommanded Product: ((2R,3S,4R,5R)-5-(6-Aminopurin-9-yl)-3,4-dihydroxy-oxolan-2-yl)methoxy-((((2R,3S,4R,5R)-5-(3-carbamoyl-4H-pyridin-1-yl)-3,4-dihydroxy-oxolan-2-yl)methoxy)hydroxyphosphoryl)oxyphosphinic acid disodium salt.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate

Carrasco, Begona; Moreno-del Alamo, Maria; Torres, Ruben; Alonso, Juan Carlos published the artcile< PcrA dissociates RecA filaments and the SsbA and RecO mediators counterbalance such activity>, Electric Literature of 606-68-8, the main research area is PcrA RecA filaments SsbA RecO mediator counterbalance activity; ATPase; RecA; RecO; SsbA; UvrD; strand exchange.

PcrA depletion is lethal in wild-type Bacillus subtilis cells. The PcrA DNA helicase contributes to unwinding RNA from the template strand, backtracking the RNA polymerase, rescuing replication-transcription conflicts, and disassembling RecA from single-stranded DNA (ssDNA) by poorly understood mechanisms. We show that, in the presence of RecA, circa one PcrA/plasmid-size circular ssDNA (cssDNA) mol. hydrolyzes ATP at a rate similar to that on the isolated cssDNA. PcrA K37A, which poorly hydrolyzes ATP, fails to displace RecA from cssDNA. SsbA inhibits and blocks the ATPase activities of PcrA and RecA, resp. RecO partially antagonizes and counteracts the neg. effect of SsbA on PcrA- and RecA-mediated ATP hydrolysis, resp. Conversely, multiple PcrA mols. are required to inhibit RecA·ATP-mediated DNA strand exchange (DSE). RecO and SsbA poorly antagonize the PcrA inhibitory effect on RecA.ATP-mediated DSE. An iterative translocating PcrA monomer strips RecA from cssDNA to prevent unnecessary recombination with the mediators SsbA and RecO balancing such activity; and a PcrA cluster that disrupts DNA transactions, as RecA-mediated DSE.

Frontiers in Molecular Biosciences published new progress about Bacillus subtilis. 606-68-8 belongs to class chiral-phosphine-ligands, and the molecular formula is C21H27N7Na2O14P2, Electric Literature of 606-68-8.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate

Tanaka, Rie; Noguchi, Keiichi; Tanaka, Ken published the artcile< Rhodium-catalyzed asymmetric reductive cyclization of heteroatom-linked 5-alkynals with heteroatom-substituted acetaldehydes>, Related Products of 139139-86-9, the main research area is heteroatom alkynal acetaldehyde rhodium catalyst asym reductive cyclization.

We have established that a cationic rhodium(I)/H8-BINAP complex catalyzes the asym. reductive cyclization of heteroatom-linked 5-alkynals with heteroatom-substituted acetaldehydes in good yields with outstanding enantioselectivity.

Journal of the American Chemical Society published new progress about Alkynals Role: RCT (Reactant), RACT (Reactant or Reagent). 139139-86-9 belongs to class chiral-phosphine-ligands, and the molecular formula is C44H40P2, Related Products of 139139-86-9.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate

Suda, Takeshi; Noguchi, Keiichi; Tanaka, Ken published the artcile< Rhodium-Catalyzed Asymmetric Formal Olefination or Cycloaddition: 1,3-Dicarbonyl Compounds Reacting with 1,6-Diynes or 1,6-Enynes>, Product Details of C44H40P2, the main research area is dicarbonyl stereoselective olefination diyne enyne rhodium BINAP segphos catalyst.

The Rh(I)/(R)-H8-BINAP complex was used as the catalyst in the asym. intermol. olefination of enolizable 1,3-dicarbonyl compounds with 1,6-diynes by [2+2+2]cycloaddition followed by electrocyclic ring opening. The same reaction was also accomplished with 1,6-enynes by using Rh(I)/S-segphos as catalyst.

Angewandte Chemie, International Edition published new progress about Alkadiynes Role: RCT (Reactant), RACT (Reactant or Reagent). 139139-86-9 belongs to class chiral-phosphine-ligands, and the molecular formula is C44H40P2, Product Details of C44H40P2.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate

Tanaka, Ken; Fukawa, Naohiro; Suda, Takeshi; Noguchi, Keiichi published the artcile< One-Step Construction of Five Successive Rings by Rhodium-Catalyzed Intermolecular Double [2+2+2] Cycloaddition: Enantioenriched [9]Helicene-Like Molecules>, COA of Formula: C44H40P2, the main research area is tetrayne diyne intermol cycloaddition rhodium catalyst; helicene asym preparation crystal mol structure.

The synthesis of [9]helicene-like mols. by rhodium-catalyzed intermol. double [2+2+2] cycloadditions is presented. Crystal structure and photophys. data for the compounds are also determined

Angewandte Chemie, International Edition published new progress about Alkadiynes Role: RCT (Reactant), SPN (Synthetic Preparation), RACT (Reactant or Reagent), PREP (Preparation). 139139-86-9 belongs to class chiral-phosphine-ligands, and the molecular formula is C44H40P2, COA of Formula: C44H40P2.

Referemce:
Phosphine ligand,
Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate