189884-53-5Relevant academic research and scientific papers
Highly Regio- A nd Enantioselective Hydrogenation of Conjugated α-Substituted Dienoic Acids
Liu, Xian,Liu, Song,Wang, Quanjun,Zhou, Gang,Yao, Lin,Ouyang, Qin,Jiang, Ru,Lan, Yu,Chen, Weiping
, p. 3149 - 3154 (2020/04/09)
Highly regio- A nd enantioselective hydrogenation of conjugated α-substituted dienoic acids was realized for the first time using Trifer-Rh complex, providing a straightforward method for the synthesis of chiral α-substituted ?,?′-unsaturated acids. DFT calculations revealed N+H-O hydrogen bonding interaction is formed to stabilize the transition state and the coordination of 4,5-double bond to Rh(III) center would facilitate the reductive elimination process. This hydrogenation provided a gram-scale synthesis of the precursor of sacubitril.
Enantioselective total synthesis of (+)-ophiobolin A
Tsuna, Kazuhiro,Noguchi, Naoyoshi,Nakada, Masahisa
supporting information, p. 5476 - 5486 (2013/06/05)
The enantioselective total synthesis of (+)-ophiobolin A is described. This total synthesis features the construction of the spiro CD ring of (+)-ophiobolin A through a stereoselective intramolecular Hosomi-Sakurai cyclization reaction, the joining of the
Ruthenium-catalysed linear-selective allylic alkylation of allyl acetates
Kawatsura, Motoi,Ata, Fumio,Wada, Shohei,Hayase, Shuichi,Uno, Hidemitsu,Itoh, Toshiyuki
, p. 298 - 300 (2007/10/03)
The regioselectivity in the ruthenium-catalysed allylic alkylation of mono substituted allyl acetates with the malonate anion was highly controlled by Ru3(CO)12 with 2-(diphenylphosphino)benzoic acid, and the linear-type alkylated product was obtained. The Royal Society of Chemistry.
Retention of regiochemistry of monosubstituted allyl acetates in the ruthenium catalysed allylic alkylation with malonate anion
Kawatsura, Motoi,Ata, Fumio,Hayase, Shuichi,Itoh, Toshiyuki
, p. 4283 - 4285 (2008/03/28)
In the RuCl2(p-cymene)/PPh3 catalysed regioselective allylic alkylation of monosubstituted allyl acetates with malonate anion, the selective substitution at the position originally substituted with acetate was observed. The Royal Society of Chemistry.
Synthetic studies on (+)-ophiobolin A: Asymmetric synthesis of the spirocyclic CD-ring moiety
Noguchi, Naoyoshi,Nakada, Masahisa
, p. 2039 - 2042 (2007/10/03)
Asymmetric synthesis of the spirocyclic CD-ring moiety of (+)-ophiobolin A is described. Fragment A, which was prepared via pig liver esterase (PLE)-mediated kinetic resolution, and fragment B, which was prepared via diastereoselective allylation and subs
Microwave-enhanced Pd(0)/acetic acid catalyzed allylation reactions of C, N, and O-pronucleophiles with alkynes
Patil, Nitin T.,Nawaz Khan,Yamamoto, Yoshinori
, p. 8497 - 8499 (2007/10/03)
An efficient method for the allylation of C, N, and O-nucleophiles with alkynes under solvent-free conditions and by microwave activation is established. The process can be termed as a real eco-chemical process since no waste elements are produced in the
Barbituric acid derivatives as inhibitors of TNF-alpha converting enzyme (TACE) and/or matrix metalloproteinases
-
Page 34, (2008/06/13)
The present application describes novel barbituric acid derivatives of formula I: or pharmaceutically acceptable salt or prodrug forms thereof, wherein A, B, L, R1, R2, R3, R4, R5, n, W, U, X, Y, Z, U
Solvent-dependent dynamic kinetic asymmetric transformation/kinetic resolution in molybdenum-catalyzed asymmetric allylic alkylations
Hughes, David L.,Palucki, Michael,Yasuda, Nobuyoshi,Reamer, Robert A.,Reider, Paul J.
, p. 2762 - 2768 (2007/10/03)
Catalytic asymmetric alkylation reactions of branched racemic carbonates 1a and 1b with sodium dimethyl malonate, promoted by molybdenum and ligand 5, proceed by a kinetic resolution in toluene, THF, tetrahydropyran, i-PrOAc, 1,2-dichloroethane, and MeCN with krel of 7-16. In THF, MeCN, tetrahydropyran, and i-PrOAc using the (S,S)-5 ligand, the fast reacting (S)-carbonate enantiomer provides the branched product with high ee (97-99.5%) and branched/linear selectivity, but the ee erodes as the reaction of the slow-reacting (R)-enantiomer takes place. This implies that the rate of equilibration of the oxidative addition complexes in these solvents is competitive with the subsequent malonate displacement step. In toluene and dichloroethane, the ee and branched/linear ratios diminish during the reaction of the slow-reacting (R)-isomer, but not nearly as much as in the other solvents. This is most likely due to either an increase in the rate of equilibration of the oxidative addition complexes relative to the malonate displacement step, or vice versa. Because of the minimal stereochemical memory effect in toluene and 1,2-dichloroethane, the reactions in these solvents can be carried to completion (dynamic kinetic asymmetric transformation) and still provide product with excellent ee (>95%). The anion of dimethyl methylmalonate also reacts via a kinetic resolution, although the ee's, rates, and krel values differ from those of the reactions with dimethyl malonate.
Molybdenum(0) and tungsten(0) catalysts with enhanced reactivity for allylic substitution: Regioselectivity and solvent effects
Malkov,Baxendale,Mansfield,Kocovsky
, p. 1234 - 1240 (2007/10/03)
The binuclear Mo(II) and W(II) complexes 28a,b and 29a,b have been developed as pre-catalysts for allylic substitution with β-dicarbonyl nucleophiles. These complexes are reduced in situ to Mo(0) and W(0) catalytic species 30a,b and 31a,b by excess of NaH, employed to generate sodiomalonate nucleophiles, or by DIBAL-H. 1,3-Dioxolane and 1,4-dioxane, when used as solvents, substantially accelerate the reaction. These new catalysts exhibit "traditional" Mo regiochemistry, i.e., the nucleophilic attack occurring preferentially at the more substituted carbon (5 → 9; 37 → 38), unless an additional factor, such as further coordination to another moiety of the allylic electrophile takes part (41), as in the case of the geranyl-type substrates (32 or 33 → 36).
Oxidative addition of allylic substrates to coordinatively unsaturated ruthenium compounds, [Ru(η5-C5Me5)(η-amidinate)]: Preparation, structure elucidation, and catalysis of novel ruthenium (IV)-η3-allyl complexes
Kondo, Hideo,Kageyama, Akira,Yamaguchi, Yoshitaka,Haga, Masa-Aki,Kirchner, Karl,Nagashima, Hideo
, p. 1927 - 1937 (2007/10/03)
Oxidative addition reactions of allylic halides, acetates, and carbonates with [Ru(η5-C5Me5)(η-amidinate)] [amidinate: iPrNC(Me)=NiPr (1a), 1BuNC(Ph)=N1Bu (1b)], which shows signs of coordinative unsaturation, gave novel cationic π-allyl ruthenium(IV) species. The compounds [Ru(η3-allyl)(η5-C5Mes)(η 2-amidinate)]+X- were isolated by anion exchange of the products (X = PF6, BF4, BPh4), and were characterized by spectroscopic analysis. The crystallography of two of the [Ru(η3-allyl)(η5-C5Mes)(η 2-amidinate)] +X- revealed a four-legged piano stool structure in which two nitrogen atoms in the amidinate ligand and two carbon atoms in the η3-allyl ligands occupy the positions of four legs; the orientation of the η3-allyl ligand was endo. Although cyclic voltammograms of the precursor, [Ru(η5-C5Me5)(η-amidinate)], indicated possible oxidative addition of organic halides other than allylic halides to [Ru(η5-C5Me5)(η-amidinate)], only allylic halides gave the corresponding Ru(IV) products. The importance of prior coordination of the carbon-carbon double bond of allylic substrates was evidenced by NMR observation of the intermediate in the reaction of 1a or 1b with allyl acetate. Addition of nucleophiles such as PhLi, dimethyl methylsodiomalonate, and piperidine to the [Ru(η3-allyl)(η5-C5Me 5)(η2-amidinate)]+X- gave rise to allylation of these nucleophiles and regeneration of [Ru(η5-C5Me5)(η-amidinate)]. The reactions of allyl methyl carbonate with nucleophiles were also achieved by catalysis of either [Ru(η5C5Me5)(η-amidinate)] or [Ru(η3-allyl)(η5-C5Me 5)(η2-amidinate)]+X-.
