32665-23-9Relevant articles and documents
Palladium-Catalyzed Carbonylation of sec- and tert-Alcohols
Dong, Kaiwu,Sang, Rui,Liu, Jie,Razzaq, Rauf,Franke, Robert,Jackstell, Ralf,Beller, Matthias
supporting information, p. 6203 - 6207 (2017/05/22)
A general palladium-catalyzed synthesis of linear esters directly from sec- and tert-alcohols is described. Compared to the classic Koch–Haaf reaction, which leads to branched products, this new transformation gives the corresponding linear esters in high yields and selectivity. Key for this protocol is the use of an advanced palladium catalyst system with L2 (pytbpx) as the ligand. A variety of aliphatic and benzylic alcohols can be directly used and the catalyst efficiency for the benchmark reaction is outstanding (turnover number up to 89 000).
Transfer Hydrogenation of Nitriles, Olefins, and N-Heterocycles Catalyzed by an N-Heterocyclic Carbene-Supported Half-Sandwich Complex of Ruthenium
Mai, Van Hung,Nikonov, Georgii I.
, p. 943 - 949 (2016/05/09)
In the presence of KOBut, N-heterocyclic carbene-supported half-sandwich complex [Cp(IPr)Ru(pyr)2][PF6] (3) (IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) catalyzes transfer hydrogenation (TH) of nitriles, activated N-heterocycles, olefins, and conjugated olefins in isopropanol at the catalyst loading of 0.5%. The TH of nitriles leads to imines, produced as a result of coupling of the initially formed amines with acetone (produced from isopropanol), and showed good chemoselectivity. Reduction of N-heterocycles occurs for activated polycyclic substrates (e.g., quinoline) and takes place exclusively in the heterocycle. The TH also works well for linear and cyclic olefins but fails for trisubstituted substrates. However, the C = C bond of α,β-unsaturated esters, amides, and acids is easily reduced even for trisubstituted species, such as isovaleriates. Mechanistic studies suggest that the active species in these catalytic reactions is the trihydride Cp(IPr)RuH3 (5), which can catalyze these reactions in the absence of any base. Kinetic studies are consistent with a classical inner sphere hydride-based mechanism of TH.
A general and enantioselective approach to pentoses: A rapid synthesis of PSI-6130, the nucleoside core of sofosbuvir
Peifer, Manuel,Berger, Rapha?lle,Shurtleff, Valerie W.,Conrad, Jay C.,Macmillan, David W. C.
supporting information, p. 5900 - 5903 (2014/05/20)
An efficient route towards biologically relevant pentose derivatives is described. The de novo synthetic strategy features an enantioselective α-oxidation reaction enabled by a chiral amine in conjunction with copper(II) catalysis. A subsequent Mukaiyama aldol coupling allows for the incorporation of a wide array of modular two-carbon fragments. Lactone intermediates accessed via this route provide a useful platform for elaboration, as demonstrated by the preparation of a variety of C-nucleosides and fluorinated pentoses. Finally, this work has facilitated expedient syntheses of pharmaceutically active compounds currently in clinical use.
Hydroalkoxycarbonylation of olefins in the presence of palladium phosphine complexes: High activity and regioselectivity
Chepaikin,Bezruchenko,Suerbaev,Shalmagambetov
, p. 117 - 121 (2007/10/03)
Several types of catalyst systems were examined in the olefin hydroalkoxycarbonylation reaction. The systems contained Pd(PPh 3)4, PdCl2(PPh3)2, or some other palladium compounds as a principal component. The second component (promoter) was p-toluenesulfonic acid or diphenyl(m-sulfophenyl)phosphine, which combines both the ligand and promoter functions. An important feature of these systems is their high activity in the hydroalkoxycarbonylation of ethylene and a high regioselectivity (83-100%) in the hydroalkoxycarbonylation of α-olefins with respect to linear products. Thus, it was unnecessary to introduce additional stabilizing ligands to augment the catalyst and promoter. The esters obtained can find application in the pharmaceutical industry and perfumery, as well as in other industries. Nauka/Interperiodica 2006.
Structure-function correlation in lipase catalysed esterification reactions of short and medium carbon chain length alcohols and acids
Divakar, Soundar
, p. 1919 - 1922 (2007/10/03)
An attempt has been made to correlate the carbon chain lengths of acids and alcohols to the extent of esterification in the Rhizomucor miehei lipase catalyzed esterification reactions involving acids of carbon chain length C2-C5 and alcohols of carbon chain length C1-C8.
Syntheses based on monocarbon molecules: IV.1 catalytic regioselective hydroalkoxycarbonylation of olefins with carbon monoxide and alcohols in the presence of the system PdCl2-PPh3-p-TsOH. perfumes from esters
Suerbaev,Shalmagambetov,Zhubanov
, p. 1927 - 1928 (2007/10/03)
Regioselective hydroalkoxycarbonylation of α-alkenes with carbon monoxide and alcohols in the presence of the system PdCl2-PPh3-p-TsOH was used to prepare a series of linear esters. Comparative characterization of some of the products (by admixture contents) with the same compounds synthesized by a commercial procedure (esterification of carboxylic acids with alcohols) was performed.
Alkylations Using Methyltrialkoxyphosphonium Tetrafluoroborate Salts. Synthetic and Mechanistic Aspects of Methyl, Ethyl, 2-Propyl, and 2-Octyl Group Transfers
Fry, Slaton E.,Pienta, Norbert J.
, p. 4877 - 4880 (2007/10/02)
Trialkyl phosphites, (RO)3P for R = methyl, ethyl, 2-propyl, and 2-octyl, were alkylated with Meerwein's salt (Me3O+BF4-) to yield the corresponding trialkoxymethylphosphonium tetrafluoroborate salts.These salts, which are all molten at room temperature, were reacted neat or in solvents with a series of nucleophiles.Thus, a variety of O, N, S, and halogen nucleophiles reacted by substitution at the R group C-O bond to give high yields after a trivial workup procedure.Rates of reaction were measured for substituted benzoic acids (4-XC6H4CO2H; X= CH3, t-Bu, CH3O, H, CF3, CN, NO2) with the neat salts under pseudo-first-order conditions or with the salt in CH3CN under second order conditions.The resulting Hammett plots indicate very little change in sensivity to the substituents when R = isopropyl compared with R = methyl and when the salt itself instead of CH3CN is solvent.
