4676-51-1Relevant academic research and scientific papers
Cyanide-Coordination Effect on Photochemical Carbon-Skeleton Rearrangements of Alkyl Ligands Coordinated to Vitamin B12 Model Complexes
Murakami, Yukito,Hisaeda, Yoshio,Ozaki, Toshiaki,Ohno, Terubisa,Fan, Sheng-Di,Matsuda, Yoshihisa
, p. 839 - 842 (1988)
The cyanide ion induced the heterolytic cleavage of the cobalt-carbon bond involved in vitamin B12 model complexes by its coordination to the central cobalt atom and enhanced the carbon-skeleton rearrangements via formation of anionic intermedi
Enantioselective hydrogenation of itaconic acid and its derivates with sol-gel immobilized Rh/BPPM catalysts
Volovych,Schwarze,Hamerla,Blum,Schom?cker
, p. 359 - 367 (2013)
Itaconic acid and some of its derivates were hydrogenated with sol-gel entrapped Rh/BPPM catalysts in methanol solutions. The immobilization process was carried out by different gel building agents: hydrophilic tetramethyl orthosilicate Si(OMe)4 (TMOS) and tetraethyl orthosilicate Si(OEt)4 (TEOS), hydrophobic triethoxyphenylsilane PhSi(OEt) 3/TMOS and trimethoxy(octyl)silane OcSi(OMe)3/TMOS. The choice of the silane precursor influences the enantioselectivity and the rate of the reaction because of the hydrophobic interactions between catalyst, gel and substrate. The immobilized catalyst could be recovered and recycled several times under N2-atmosphere. About 90-99% ee were achieved for the hydrogenation of itaconic acid to (S)-(+)-2-methyl succinic acid, and about 14% ee for the hydrogenation of dimethylitaconate to (S)-(+)-2-methyl-succinic acid dimethylester.
Preparation method and application of sacubitril intermediate
-
, (2021/07/17)
The invention discloses a preparation method and application of a sacubitril intermediate. The sacubitril intermediate disclosed by the invention is obtained by taking itaconic anhydride as a raw material, performing chiral reduction, esterification, selective hydrolysis and carboxyl activation, and finally conducting coupling with 4-biphenylacetic acid. The invention also provides a method for preparing sacubitril by using the sacubitril intermediate. The preparation method provided by the invention has the advantages of easily available raw materials, simple process, economy, environmental protection and the like, and is more suitable for industrial production compared with other routes.
Reduction of Activated Alkenes by PIII/PV Redox Cycling Catalysis
Longwitz, Lars,Werner, Thomas
supporting information, p. 2760 - 2763 (2020/02/05)
The carbon–carbon double bond of unsaturated carbonyl compounds was readily reduced by using a phosphetane oxide catalyst in the presence of a simple organosilane as the terminal reductant and water as the hydrogen source. Quantitative hydrogenation was observed when 1.0 mol % of a methyl-substituted phosphetane oxide was employed as the catalyst. The procedure is highly selective towards activated double bonds, tolerating a variety of functional groups that are usually prone to reduction. In total, 25 alkenes and two alkynes were hydrogenated to the corresponding alkanes in excellent yields of up to 99 %. Notably, less active poly(methylhydrosiloxane) could also be utilized as the terminal reductant. Mechanistic investigations revealed the phosphane as the catalyst resting state and a protonation/deprotonation sequence as the crucial step in the catalytic cycle.
Diastereo- and Enantioselective Synthesis of Fluorine Motifs with Two Contiguous Stereogenic Centers
Ponra, Sudipta,Rabten, Wangchuk,Yang, Jianping,Wu, Haibo,Kerdphon, Sutthichat,Andersson, Pher G.
, p. 13878 - 13883 (2018/10/24)
The synthesis of chiral fluorine containing motifs, in particular, chiral fluorine molecules with two contiguous stereogenic centers, has attracted much interest in research due to the limited number of methods available for their preparation. Herein, we report an atom-economical and highly stereoselective synthesis of chiral fluorine molecules with two contiguous stereogenic centers via azabicyclo iridium-oxazoline-phosphine-catalyzed hydrogenation of readily available vinyl fluorides. Various aromatic, aliphatic, and heterocyclic systems with a variety of functional groups were found to be compatible with the reaction and provide the highly desirable product as single diastereomers with excellent enantioselectivities.
METHOD FOR THE PRODUCTION OF METHYLSUCCINIC ACID AND THE ANHYDRIDE THEREOF FROM CITRIC ACID
-
Page/Page column 16, (2018/04/21)
A process for the preparation of methylsuccinic acid in any form, including its salts, its mono- and diester derivatives and the anhydride thereof, which comprises reacting citric acid or a derivative thereof in decarboxylation conditions, said process comprising (i) reacting citric acid or mono- and diester derivatives thereof in a non- aqueous solvent, specifically excluding alcohols, on a metallic catalyst at a temperature between 50 to 400°C and under a partial hydrogen pressure from 0.1 to 50 bar or (ii) reacting citric acid or any salt thereof or mono-, di- and triester derivatives thereof on a metallic catalyst in solvents comprising at least 5% water, at a temperature of from 50 to 400°C under a hydrogen partial pressure from 0.1 to 400 bar
PROCESS FOR DOUBLE CARBONYLATION OF ALLYL ALCOHOLS TO CORRESPONDING DIESTERS
-
Paragraph 0064; 0067; 0068, (2017/07/14)
The invention relates to a process for doubly carbonylating allyl alcohols to the corresponding diesters, wherein a linear or branched allyl alcohol is reacted with a linear or branched alkanol (alcohol) with supply of CO and in the presence of a catalytic system composed of a palladium complex and at least one organic phosphorus ligand and in the presence of a hydrogen halide selected from HCl, HBr and HI.
PROCESS FOR DOUBLE CARBONYLATION OF ALLYL ETHERS TO CORRESPONDING DIESTERS
-
Paragraph 0095; 0097, (2017/07/14)
The invention relates to a process for doubly carbonylating allyl ethers to the corresponding diesters, wherein a linear or branched allyl ether is reacted with a linear or branched alkanol (alcohol) with supply of CO and in the presence of a catalytic system composed of a palladium complex and at least one organic phosphorus ligand and in the presence of a hydrogen halide selected from HCl, HBr and HI.
Photoredox radical conjugate addition of dithiane-2-carboxylate promoted by an iridium(III) phenyl-tetrazole complex: a formal radical methylation of Michael acceptors
Gualandi, Andrea,Matteucci, Elia,Monti, Filippo,Baschieri, Andrea,Armaroli, Nicola,Sambri, Letizia,Cozzi, Pier Giorgio
, p. 1613 - 1620 (2017/02/10)
A readily accessible iridium(iii) phenyl-tetrazole complex ([Ir(ptrz)2(tBu-bpy)]+, 2; Hptrz = 2-methyl-5-phenyl-tetrazole; tBu-bpy = 4,4′-di-tert-butyl-2,2′-bipyridine) is shown to be a versatile catalyst for a new photocatalytic Michael reaction. Under light irradiation in the presence of 2, a dithiane 2-carboxylic acid, obtained by simple hydrolysis of a commercially available ethyl ester, generates a 1,3-dithiane radical capable of performing addition to a variety of Michael acceptors (e.g., unsaturated ketones, esters, amides and malonates). This broad scope reaction with high yields is a formal photo-redox addition of the elusive methyl radical and the adducts obtained can be starting materials for a variety of functionalized products. The excited-state oxidation potential of catalyst 2 allows selective formation of radicals only from α-heterosubstituted carboxylates. Chemical modification of this metal complex can tune the electrochemical properties, opening a route to new highly selective catalytic photo-oxidation reactions.
Transfer hydrogenation promoted by N-heterocyclic carbene and water
Kato, Terumasa,Matsuoka, Shin-Ichi,Suzuki, Masato
supporting information, p. 13906 - 13909 (2015/09/07)
N-Heterocyclic carbenes (NHCs) promote the transfer hydrogenation of various activated C=C, C=N, and N=N bonds with water as the proton source. The NHCs act as reducing reagents to be converted into their oxides. A detailed reaction mechanism is proposed on the basis of deuterium-labeling experiments.
