52386-78-4Relevant academic research and scientific papers
Mechanistically Guided One Pot Synthesis of Phosphine-Phosphite and Its Implication in Asymmetric Hydrogenation
Sen, Anirban,Kumar, Rohit,Pandey, Swechchha,Vipin Raj,Kumar, Pawan,Vanka, Kumar,Chikkali, Samir H.
supporting information, (2022/01/11)
Although hybrid bidentate ligands are known to yield highly enantioselective products in asymmetric hydrogenation (AH), synthesis of these ligands is an arduous process. Herein, a one pot, atom-economic synthesis of a hybrid phosphine-phosphite (L1) is reported. After understanding the reactivity difference between an O-nucleophile versus C-nucleophile, one pot synthesis of Senphos (L1) was achieved (72 %). When L1 was treated with [Rh], 31P NMR revealed bidentate coordination to Rh. Senphos, in the presence of rhodium, catalyzes the AH of Methyl-2-acetamido-3-phenylacrylate and discloses an unprecedented turn over frequency of 2289, along with excellent enantio-selectivity (92 %). The generality is demonstrated by hydrogenating an array of alkenes. The AH operates under mild conditions of 1–2 bar H2 pressure, at room temperature. The practical relevance of L1 is demonstrated by scaling-up the reaction to 1 g and by synthesizing DOPA, a drug widely employed for the treatment of Parkinson's disease. Computational insights indicate that the R isomer is preferred by 3.8 kcal/mol over the S isomer.
Chiral bisphosphine ligands based on quinoline oligoamide foldamers: application in asymmetric hydrogenation
Zheng, Lu,Zheng, Dan,Wang, Yanru,Yu, Chengyuan,Zhang, Kun,Jiang, Hua
supporting information, p. 9573 - 9577 (2019/11/20)
A series of chiral bisphosphine ligands were designed and synthesized based on single-handed quinoline oligoamide foldamers. The bisphosphine ligands can coordinate with Rh(cod)2BF4 in a 1 : 1 stoichiometry and the resulted chiral Rh(i) catalysts were applied in the asymmetric hydrogenation of α-dehydroamino acid esters, in which excellent conversions and promising levels of enantioselectivity were achieved.
BABIPhos Family of Biaryl Dihydrobenzooxaphosphole Ligands for Asymmetric Hydrogenation
Li, Guisheng,Zatolochnaya, Olga V.,Wang, Xiao-Jun,Rodríguez, Sonia,Qu, Bo,Desrosiers, Jean-Nicolas,Mangunuru, Hari P. R.,Biswas, Soumik,Rivalti, Daniel,Karyakarte, Shuklendu D.,Sieber, Joshua D.,Grinberg, Nelu,Wu, Ling,Lee, Heewon,Haddad, Nizar,Fandrick, Daniel R.,Yee, Nathan K.,Song, Jinhua J.,Senanayake, Chris H.
supporting information, p. 1725 - 1729 (2018/04/14)
Novel bidentate phosphine ligands BABIPhos featuring a biaryl bis-dihydrobenzooxaphosphole core are presented. Their synthesis was achieved via Pd-catalyzed reductive homocoupling of dihydrobenzooxaphosphole aryl triflates. An efficient route toward various analogues was also established, giving access to phosphines with different electronic and steric properties. The newly obtained ligands demonstrated high efficiency and selectivity in Rh-catalyzed asymmetric hydrogenation of di- and trisubstituted enamides. This new class of ligands is complementary to previously described bidentate benzooxaphosphole ligands BIBOP.
Elucidation of Racemization Process of Azaspirene Skeleton in Neutral Aqueous Media
Hirasawa, Shun,Mukai, Ken,Sakai, Shinnosuke,Wakamori, Shinnosuke,Hasegawa, Takahiro,Souma, Kazunori,Kanomata, Nobuhiro,Ogawa, Narihito,Aizawa, Mamoru,Emoto, Makoto
, p. 14457 - 14464 (2019/01/03)
Azaspirene and related congeners, which possess various biological activities, have a unique spirocyclic core structure. However, there are few studies on the chemical properties of (-)-azaspirene, despite the fact that it may provide important insights into unveiling the biosynthetic pathway. Here, we report a nine-step chemical synthesis of an azaspirene analogue with a new finding that the natural (-)-azaspirene skeleton easily racemizes in neutral aqueous media.
Modular solid-phase synthesis, catalytic application and efficient recycling of supported phosphine-phosphite ligand libraries
Heutz, Frank J. L.,Kamer, Paul C. J.
supporting information, p. 2116 - 2123 (2016/02/09)
In spite of decades of research in the field of homogeneous asymmetric catalysis the discovery of new high performance catalysts still relies heavily on trial-and-error. There is still a lack of efficient combinatorial methods which enable the synthesis and screening of vast ligand libraries, especially for bidentate phosphorus ligands. Here we present a highly modular solid-phase synthetic approach which provides facile access to libraries of phosphine-phosphite ligands in quantitative yield requiring only minimal work-up. The obtained library of supported phosphine-phosphites was successfully applied in rhodium catalyzed asymmetric hydrogenation obtaining high enantioselectivities up to 98%. Also, these polymer supported ligands could be successfully recycled under batch conditions exhibiting only a small decline of activity and no loss of selectivity.
Catalytic, asymmetric, and stereodivergent synthesis of non-symmetric β,β-Diaryl-α-Amino Acids
Molinaro, Carmela,Scott, Jeremy P.,Shevlin, Michael,Wise, Christopher,Mnard, Alain,Gibb, Andrew,Junker, Ellyn M.,Lieberman, David
, p. 999 - 1006 (2015/01/30)
We report a concise, enantio- and diastereoselective route to novel nonsymmetrically substituted N-protected β,β-diaryl-α-amino acids and esters, through the asymmetric hydrogenation of tetrasubstituted olefins, some of the most challenging examples in the field. Stereoselective generation of an E- or Z-enol tosylate, when combined with stereoretentive Suzuki-Miyaura cross-coupling and enantioselective hydrogenation catalyzed by (NBD)2RhBF4 and a Josiphos ligand, allows for full control over the two vicinal stereogenic centers. High yields and excellent enantioselectivities (up to 99% ee) were obtained for a variety of N-acetyl, N-methoxycarbonyl, and N-Boc β,β-diaryldehydroamino acids, containing a diverse and previously unreported series of heterocyclic and aryl substituted groups (24 examples) and allowing access to all four stereoisomers of these valuable building blocks.
Enantiomerically Enriched Aminodiphosphines as Ligands for the Preparation of Catalysts for Asymmetric Synthesis
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Page/Page column 14, (2012/12/14)
The present invention relates to enantiomerically enriched aminodiphosphine ligands where the chirality is located in the phosphorus atom and their preparation process, to catalysts containing them and their preparation process, as well as their use in as
Rhodium/olefin-catalyzed reaction of arylboronic acids with an α-acetamido acrylic ester: Mizoroki-Heck-type reaction versus asymmetric conjugate addition
Noel, Timothy,Goek, Yasar,Eycken, Johan Van der
experimental part, p. 540 - 543 (2010/08/03)
In this paper we present our results concerning the rhodium/olefin-catalyzed reaction of arylboronic acids with an α-acetamido acrylic ester. With a chiral norbornadiene ligand rather low enantioselectivities (up to 21% ee) were obtained. Besides the expected conjugate adduct, we also observed the formation of a significant amount of Mizoroki-Heck-type product. The ratio of the conjugate adduct/Mizoroki-Heck product could be adjusted by a proper choice of the olefin ligand.
Amino acid based phosphoramidite ligands for the rhodium-catalyzed asymmetric hydrogenation
Breuil, Pierre-Alain R.,Reek, Joost N. H.
supporting information; experimental part, p. 6225 - 6230 (2010/03/26)
Two sets of amino acid based phosphoramidite ligands with either a BINOL backbone (Sb-1a-e and Rb-1a) or a flexible biphenol backbone (2a-c and 2f) were synthesized and evaluated in the rhodium-catalyzed hydrogenation of different fu
Metal Ion Effects in Intramolecular Reactions. Effects of Divalent Metal Ions on Intramolecular Acetamido Group Participation in Ester Hydrolysis
Fife, Thomas H.,Przystas, Theodore J.,Pujari, Mahesh P.
, p. 8157 - 8163 (2007/10/02)
The hydrolysis reactions of a series of esters of α-acetamidocinnamic acid proceed with formation of an oxazolinone intermediate.In 50percent dioxane-H2O (v/v) at 50 deg C, an oxazolinone can be observed spectrophotometrically in the OH- catalyzed cyclization reactions of the α-acetamido-substituted esters with leaving groups of pKa 12.4 or less.In comparison with the OH- catalyzed hydrolysis of the corresponding cinnamate esters, the rate enhancement due to the presence of the acetamido group is a factor of 200 with the trifluoroethyl ester and increases to 2x1E6 with the p-nitrophenyl ester.The plot of log kOH vs ?, the Hammett substituent constant, is linear and has a slope (ρ) of 2.7 (1.8 when ?- is employed) for the cyclization reactions of the phenolic esters, but the ρ value is only 1.4 for the OH- catalyzed hydrolysis of the corresponding cinnamates.The slope of log kOH vs the pKa of the leaving group for the cyclization of the α-acetamidocinnamic acid derivatives, βlg, is -0.9.Thus, there must be considerable C-O bond breaking in the critical transition state for oxazolinone formation.In H2O as the solvent, 6-carboxy-2-pyridylmethyl α-(N-acetylamino)cinnamate and the corresponding 2-pyridylmethyl derivative cyclize rapidly to the oxazolinone with KOH (5xE4)-fold larger than that for hydrolysis of 2-pyridylmethyl cinnamate, even though the leaving group is an aliphatic alcohol.There is significant metal ion catalysis in the cyclization reactions with Cu2+, Ni2+, Co2+ or Zn2+.The binding of the metal ions to the 6-carboxy-substituted derivative is very strong, and saturation occurs at metal ion concentrations less than 0.01 M.A saturating concentration of Cu2+ (0.001 M) enhances the rate of cyclization by a factor of 5x1E4.Thus, the total rate enhancement provided by bifunctional catalysis (Cu2+ and the neighboring acetamido group) is 1E9-fold.Metal ion binding to 2-pyridylmethyl α-(N-acetylamino)cinnamate is weak, but nevertheless, the second-order rate constants kOH are similar to those of the 6-carboxy-substituted ester at equal metal ion concentrations.The metal ions must exert their catalytic effect by stabilizing the leaving group alcohol in the transition state.This appears to be a general mechanism for metal ion catalysis of reactions in which C-O bond breaking is the rate-determining step.
