- Isomerizing Methoxycarbonylation of Alkenes to Esters Using a Bis(phosphorinone)xylene Palladium Catalyst
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The synthesis and characterization of bulky diphosphine 1,2-bis(4-phosphorinone)xylene, BPX, and its palladium complexes [(BPX)PdCl2] and [(BPX)Pd(O2CCF3)2] are described. BPX was evaluated as a ligand in Pd-catalyzed isomerizing methoxycarbonylation. A broad range of alkenes, including terminal, internal, branched, and functionalized alkenes, can be converted to esters with activities and selectivities matching or surpassing the performance of the state-of-the-art palladium bis(di(tert-butyl)phosphino-o-xylene (Pd-DTBPX) catalyst. A molecular structure of the precatalyst [(BPX)Pd(O2CCF3)2] was obtained showing a square planar geometry and a bite angle of 100.11(3)°. Rhodium carbonyl complexes [(BPX)Rh(CO)Cl] and [(DTBPX)Rh(CO)Cl] were synthesized to compare the relative electronic parameters, revealing a ν(C≡O) of 1956.8 and 1948.3 cm-1, respectively, suggesting a reduced ability of BPX to donate electron density to the metal relative to DTBPX. Competitive protonation experiments between BPX and DTBPX in the presence of CH3SO3H exclusively produce [DTBPX(H)2]2+, providing additional evidence that BPX is a much weaker base than DTBPX. This could be due to either the effect of the electron-withdrawing ketone group in the phosphorinone ring or the compression of the C-P-C bond angle induced by the ring structure. The 31P NMR (CDCl3) chemical shift of BPX is 5.6 ppm, upfield of DTBPX at 27.6 ppm. This anomalous result is attributed to a strong gamma substituent effect of C=O in the BPX ligand. The improved activity of Pd-BPX, relative to Pd-DTBPX, could be attributed to a more electrophilic PdII center, which could accelerate the rate-determining methanolysis step.
- Nobbs, James D.,Low, Choon Heng,Stubbs, Ludger P.,Wang, Cun,Drent, Eite,Van Meurs, Martin
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p. 391 - 398
(2017/04/26)
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- From azides to nitriles. A novel fast transformation made possible by BrF3
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(Equation Presented) Various alkyl and aryl azides, readily obtained from halides or alcohols, were transformed into the corresponding nitrites using bromine trifluoride in moderate to good yields. The reaction is general and gives positive results with aliphatic, aromatic, cyclic, and functionalized azides. It can also be applied to the synthesis of optically active nitriles.
- Sasson, Revital,Rozen, Shlomo
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p. 2177 - 2179
(2007/10/03)
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- P4 cap modified tetrapeptidyl α-ketoamides as potent HCV NS3 protease inhibitors
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We describe herein the design, syntheses, and biological evaluation of new series of P4 tetrazole and adipic acid, ester, amide capped tetrapeptidyl α-ketoamide based HCV protease inhibitors.
- Sun, David X.,Liu, Lifei,Heinz, Beverly,Kolykhalov, Alexander,Lamar, Jason,Johnson, Robert B.,Wang, Q. May,Yip, Yvonne,Chen, Shu-Hui
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p. 4333 - 4338
(2007/10/03)
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- Production of alkyl 6-aminocaproate
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A process for making alkyl 6-aminocaproate by hydroformylating 3-pentenenitrile to produce 3-, 4-, and 5-formylvaleronitrile (FVN mixture), converting the FVN mixture to alkyl 3-, 4-, and 5-cyanovalerate by either oxidative esterification of the FVN mixture or oxidation of the FVN mixture followed by esterification; isolating alkyl 5-cyanovalerate; and hydrogenating the alkyl 5-cyanovalerate to produce alkyl 6-aminocaproate. The resulting alkyl 6-aminocaproate can be cyclized to produce caprolactam.
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Page column 9
(2008/06/13)
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- Carbonylation of olefinically unsaturated nitriles and acids using a sulfone solvent
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Process using selected sulfones, e.g., tetramethylenesulfone as solvents in the carbonylation of nitriles, e.g., 3-pentenenitrile and acids, e.g., 3-pentenoic acid to produce highly linear products.
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- β-CARBONYL RADICALS AS THREE-CARBON BUILDING BLOCKS FOR CARBON-CARBON BOND FORMING REACTIONS
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From aldehydes, ketones and esters β-carbonyl radicals 47 can be generated via enolization, cyclopropanation, solvomercuration and reduction with NaBH4.Radicals 47 react with electron-poor alkenes 27 to give products of CC-bond forming reactions (Tables 1-3).Carbonyl compounds are therefore precursors of three-carbon building blocks.The products result from reactions with "Umpolung".
- Giese, Bernd,Horler, Hans
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p. 4025 - 4038
(2007/10/02)
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- Manufacture of 5-cyanovaleric acid and its esters
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5-Cyanovaleric acid and its esters are manufactured by reacting pentenonitriles with water or alcohols and carbon monoxide in the presence of metal carbonyls and heterocyclic compounds at elevated temperature under pressure. 5-Cyanovaleric acid and its esters are starting materials for the manufacture of dyes, pesticides, fibers, especially nylon fibers, and plastics.
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