- Twofold C?H Activation-Based Enantio- and Diastereoselective C?H Arylation Using Diarylacetylenes as Rare Arylating Reagents
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C?H bond activation has been established as an attractive strategy to access axially chiral biaryls, and the most straightforward method is direct C?H arylation of arenes. However, the arylating source has been limited to several classes of reactive and bulky reagents. Reported herein is rhodium-catalyzed 1:2 coupling of diarylphosphinic amides and diarylacetylenes for enantio- and diastereoselective construction of biaryls with both central and axial chirality. This twofold C?H activation reaction stays contrast to the previously explored Miura–Satoh type 1:2 coupling of arenes and alkynes in terms of chemoselectivity and proceeded under mild conditions with the alkyne acting as a rare arylating reagent. Both C?H activation events are stereo-determining and are under catalyst control, with the 2nd C?H activation being diastereo-determining in a remote fashion. Analysis of the stereochemistry of the major and side products suggests moderate enantioselectivity of the initial C?H activation–desymmetrization process. However, the minor (R) rhodium vinyl intermediate is consumed more readily in undesired protonolysis, eventually resulting in high enantio- and diastereoselectivity of the major product.
- Hu, Panjie,Kong, Lingheng,Li, Xingwei,Wang, Fen,Zhu, Xiaolin
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supporting information
p. 20424 - 20429
(2021/08/09)
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- Synthesis and characterization of new PNNP-type chiral ligands
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Polydentate ligands having both soft and hard centers are very effective ligands for the preparation of transition metal complexes. PNNP-type tetradentate diaminodiphosphine ligands are most preferred ligand types cause of their good efficiency for the asymmetric reactions. In this study, three different iminophosphine derivative PNNP-type chiral ligands were synthesized using (R)-(+)-1,1′-Binaphthyl-2,2′-diamine (R-BINAM) and d?phenylphosph?no benzaldehyde derivatives.
- Tezcan, Burcu,Güzel, Bilgehan
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p. 315 - 316
(2018/12/11)
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- Method for preparing diarylphosphoryl chloride compound
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The invention discloses a method for preparing a diarylphosphochlorine compound and belongs to the field of organic synthesis. The method is as follows: the diarylphosphochlorine compound is preparedby reaction of triarylphosphine as a starting material with phosphorus trichloride in the presence of zinc trifluoromethanesulfonate as a catalyst and distillation. Compared with the prior art, the method has the advantages of high reaction yield and simple post-treatment, is particularly suitable for preparation of the diarylphosphochlorine compound with a substituent, and is more suitable for industrial production. The obtained diarylphosphochlorine compound can be used as a ligand for synthesizing metal catalysts, and is applied to the fields such as organic photoelectric materials and medicines.
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Paragraph 0018-0019
(2018/06/15)
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- Asymmetric Synthesis of Chiral Primary Amines by Ruthenium-Catalyzed Direct Reductive Amination of Alkyl Aryl Ketones with Ammonium Salts and Molecular H2
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A ruthenium/C3-TunePhos catalytic system has been identified for highly efficient direct reductive amination of simple ketones. The strategy makes use of ammonium acetate as the amine source and H2 as the reductant and is a user-friendly and operatively simple access to industrially relevant primary amines. Excellent enantiocontrol (>90% ee for most cases) was achieved with a wide range of alkyl aryl ketones. The practicability of this methodology has been highlighted by scalable synthesis of key intermediates of three drug molecules. Moreover, an improved synthetic route to the optimal diphosphine ligand C3-TunePhos is also presented.
- Tan, Xuefeng,Gao, Shuang,Zeng, Weijun,Xin, Shan,Yin, Qin,Zhang, Xumu
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supporting information
p. 2024 - 2027
(2018/02/19)
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- Diastereoselective desymmetrization of diarylphosphinous acid-borane amides under Birch reduction
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Treatment of diarylphosphinous acid-borane amides possessing chiral amido functionality with an alkali metal solution in liquid ammonia induced a preferential dearomatization of one aryl substituent at phosphorus leading to the formation of non-equimolar amounts of diastereomers. Diastereoselectivity of dearomatization depends strongly on the structure of a chiral auxiliary.
- Stankevi?, Marek
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p. 6082 - 6102
(2015/06/08)
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- Catalytic asymmetric intramolecular hydroamination of alkynes in the presence of a catalyst system consisting of Pd(0)-methyl Norphos (or tolyl Renorphos)-benzoic acid
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(Chemical Equation Presented) Enantiomerically pure methyl Norphos (A), tolyl Norphos (B), CF3 Norphos (C), methyl Renorphos (D), and tolyl Renorphos (E) were synthesized and used as chiral bisphosphine ligands for the catalyst system, Pd2(dba)3·CHCl3/PhCOOH, in an intramolecular hydroamination of aminoalkynes 15. Among the Norphos series, methyl Norphos (A) was the best ligand for the hydroamination, and the corresponding five- and six-membered nitrogen heterocycles 16 were obtained in high yields with high enantioselectivities. Among the Renorphos series, tolyl Renorphos (E) gave the best result; both methyl Norphos (A) and tolyl Renorphos (E) afforded high yields and high enantioselectivities. NMR investigation using Me-Norphos revealed that this ligand was oxidized gradually in the presence of Pd2(dba)3·CHCl3 in C6D 6 even under the conditions using Ar atmosphere to give Me-Norphos oxide, which prevented the intramolecular hydroamination. On the other hand, Me-Norphos was rather stable in C6D6 in the absence of the palladium catalyst under Ar atmosphere and was not converted to its oxide even after 3 days. The gradual oxidation of ligands (A and E) in the presence of the Pd catalyst is perhaps a reason why 20 mol % of A or E was needed to obtain high yields and high ee's of 16.
- Narsireddy, Meda,Yamamoto, Yoshinori
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experimental part
p. 9698 - 9709
(2009/04/07)
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- Lewis acid acceleration of C-N bond-forming reductive elimination from heteroarylpalladium complexes and catalytic amidation of heteroaryl bromides
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A large acceleration of carbon-nitrogen bond-forming reductive elimination from heteroarylpalladium amido complexes by addition of Lewis acids is described. Several lines of data imply that this effect arises from coordination of the Lewis acid to the nitrogen of the heteroaryl group. The presence of this coordination was confirmed by isolation of a Lewis acid base complex with a borane coordinated to the pyridyl nitrogen. This adduct underwent reductive elimination faster than the complex lacking the Lewis acid, and it occurred in high yield. Control experiments showed that this acceleration of reductive elimination was not observed for the reactions of arylpalladium amide complexes. This effect of Lewis acids translated to catalytic C-N bond-forming coupling processes. The binding of Lewis acids to the pyridyl nitrogen led to an acceleration of the amidation of unactivated heteroaryl bromides catalyzed by palladium complexes of Xantphos. The rates were faster and the yields were higher for reactions of BEt3 adducts of basic heteroaryl bromides than for the free heteroaryl bromides. This phenomenon draws parallels to the beneficial effect of Lewis acids on the reductive elimination of nitriles from arylmetal cyanide complexes and the catalytic hydrocyanation of olefins. Copyright
- Shen, Qilong,Hartwig, John F.
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p. 7734 - 7735
(2008/02/07)
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- Development of efficient and reusable diarylphosphinopolystyrene-supported palladium catalysts for C-C bond forming cross-coupling reactions
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Short and versatile syntheses of reusable diarylphosphinopolystyrene- supported palladium catalysts 3a-j are described. The bis(o-tolyl)phosphino catalyst 3b is particularly efficient for the Suzuki and Sonogashira cross-couplings, whereas the bis(m-tolyl)phosphino catalyst 3c is the most active catalyst for Heck reactions. The couplings are performed under non-anhydrous reaction conditions and require only low amounts of supported palladium (0.5 mequivs. for Suzuki-Miyaura, 1.0 mequiv. for Sonogashira and 0.5 mequivs. for Heck reactions could be sufficient). Catalysts 3a-j are recovered by filtration and can be reused more than four times with no loss of efficiency.
- Schweizer, Stephane,Becht, Jean-Michel,Le Drian, Claude
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p. 1150 - 1158
(2008/03/28)
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- (p-tolyl)dichlorophosphine and di(p-tolyl)chlorophosphine sources of new organophosphorus(III) and (V) compounds
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The purpose of our present work was to study some chemical properties of p-tolyldichlorophosphine and di(p-tolyl)chlorophosphine involved in reactions with organo-lithium compounds, with 1,2-diols and also when are reactants in variants of Reformatsky and Mannich reactions, in order to obtain some new substances of trivalent and pentavalent phosphorus useful for our further investigations. All the new phosphorus(III) and (V) compounds were obtained in fair yields, and were characterized by elemental analysis, IR, and NMR spectroscopy. They will find potential synthetic utility as convenient ligands for transition metals and reagents for the preparation of phosphonium salts, for obtaining chiral substances and as biologically active ring substances.
- Fǎgǎdar-Cosma, Eugenia,Fǎgǎdar-Cosma, Gheorghe
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p. 211 - 217
(2007/10/03)
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- Haloalkylation process
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A process for the haloalkylation of certain tin, phosphorus and germanium halides is disclosed. The process is carried out typically in a halocarbon solvent at temperatures of less than 0° C. using as the haloalkylating reagent an admixture of a haloalkyl halide and tris(lower alkylamino)phosphine.
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- Mono-, Di- and Trichloroacetylditolyl- and -dicyclohexylphosphanes
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Reaction of the acid chlorides X1X2X3CC(O)Cl (1ax-bz) with the silylphosphanes Me3SiPR2 (2a, b) results in the formation of the mono-, di- and trichloroacetylditolyl- and -dicyclohexylphosphanes X1X2X3CC(O)PR2 (3ax-bz). 3bx-bz are thermally unstable and decompose at 20 deg C to give ClP(c-C6H11)2.Stereochemical effects cause the 31P signal in the spectra of the series 3ax-az and 3bx-bz to shift to higher fields with increasing content of chlorine in the acetyl group. - Keywords: Chloroacetyldiorganylphosphanes, NMR Spectra
- Lindner, Ekkehard,Merkle, Ralf Dieter
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p. 1580 - 1582
(2007/10/02)
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