123542-72-3Relevant academic research and scientific papers
Phosphine Oxide Based Supramolecular Ligands in the Rhodium-Catalyzed Asymmetric Hydrogenation
Daubignard, Julien,Detz, Remko J.,De Bruin, Bas,Reek, Joost N. H.
, p. 3961 - 3969 (2019)
A series of bisphosphine monoxides and a phosphoramidite have been used for the preparation of supramolecular ligands. A structural analysis of the complexes using NMR spectroscopy and DFT calculations revealed the formation of strong hydrogen bonding between the two ligands. The complexes have been evaluated in the hydrogenation of several functionalized alkenes, leading to very high enantioselectivity for the substrates bearing a hydroxyl group. Also, kinetic studies showed that enhanced reaction rates of hydrogenation are observed in comparison with the supramolecular catalytic systems based on urea groups. In-depth NMR spectroscopy experiments and computational studies have highlighted the crucial role of the hydrogen bond between the phosphine oxide ligands and the substrate during the hydrogenation reaction.
Rational Optimization of Supramolecular Catalysts for the Rhodium-Catalyzed Asymmetric Hydrogenation Reaction
Daubignard, Julien,Detz, Remko J.,Jans, Anne C. H.,de Bruin, Bas,Reek, Joost N. H.
, p. 13056 - 13060 (2017)
Rational design of catalysts for asymmetric transformations is a longstanding challenge in the field of catalysis. In the current contribution we report a catalyst in which a hydrogen bond between the substrate and the catalyst plays a crucial role in determining the selectivity and the rate of the catalytic hydrogenation reaction, as is evident from a combination of experiments and DFT calculations. Detailed insight allowed in silico mutation of the catalyst such that only this hydrogen bond interaction is stronger, predicting that the new catalyst is faster. Indeed, we experimentally confirmed that optimization of the catalyst can be realized by increasing the hydrogen bond strength of this interaction by going from a urea to phosphine oxide H-bond acceptor on the ligand.
Chemoenzymatic Production of Enantiocomplementary 2-Substituted 3-Hydroxycarboxylic Acids from l-α-Amino Acids
Pickl, Mathias,Marín-Valls, Roser,Joglar, Jesús,Bujons, Jordi,Clapés, Pere
, p. 2866 - 2876 (2021/04/14)
A two-enzyme cascade reaction plus in situ oxidative decarboxylation for the transformation of readily available canonical and non-canonical l-α-amino acids into 2-substituted 3-hydroxycarboxylic acid derivatives is described. The biocatalytic cascade consisted of an oxidative deamination of l-α-amino acids by an l-α-amino acid deaminase from Cosenzaea myxofaciens, rendering 2-oxoacid intermediates, with an ensuing aldol addition reaction to formaldehyde, catalyzed by metal-dependent (R)- or (S)-selective carboligases namely 2-oxo-3-deoxy-l-rhamnonate aldolase (YfaU) and ketopantoate hydroxymethyltransferase (KPHMT), respectively, furnishing 3-substituted 4-hydroxy-2-oxoacids. The overall substrate conversion was optimized by balancing biocatalyst loading and amino acid and formaldehyde concentrations, yielding 36–98% aldol adduct formation and 91–98% ee for each enantiomer. Subsequent in situ follow-up chemistry via hydrogen peroxide-driven oxidative decarboxylation afforded the corresponding 2-substituted 3-hydroxycarboxylic acid derivatives. (Figure presented.).
Fluorinated β2- and β3-amino acids: Synthesis and inhibition of α-chymotrypsin
Peddie, Victoria,Pietsch, Markus,Bromfield, Karen M.,Pike, Robert N.,Duggan, Peter J.,Abell, Andrew D.
experimental part, p. 1845 - 1859 (2010/10/18)
The synthesis of a series of -fluorinated β2- and β3-amino acid derivatives is described. Stereoselective fluorination at the -carbon of the β3-amino acids was achieved by deprotonation with lithium diisopropylamide followed by treatment with N-fluorobenzenesulfonimide. Fluorination of β2-amino acids employed the chiral auxiliary (4R)-4-benzyl-2-oxazolidinone. The α-fluorinated amino acids and their non-fluorinated precursors were found to competitively inhibit α-chymotrypsin. Georg Thieme Verlag Stuttgart New York.
The highly enantioselective phase-transfer catalytic mono-alkylation of malonamic esters
Kim, Mi-Hyun,Choi, Sea-Hoon,Lee, Yeon-Ju,Lee, Jihye,Nahm, Keepyung,Jeong, Byeong-Seon,Park, Hyeung-Geun,Jew, Sang-Sup
supporting information; experimental part, p. 782 - 784 (2009/07/10)
The phase-transfer catalytic alkylation of N,N-dialkylmalonamic tert-butyl esters in the presence of 1 mol% of (S,S)-3,4,5-trifluorophenyl-NAS bromide afforded highly enantioselective (S)-mono-α-alkylated products (up to 96% ee), which could be readily converted into versatile chiral building blocks without loss of chirality. The Royal Society of Chemistry.
Singly hydrogen bonded supramolecular ligands for highly selective rhodium-catalyzed hydrogenation reactions
Breuil, Pierre-Alain R.,Patureau, Frederic W.,Reek, Joost N. H.
supporting information; experimental part, p. 2162 - 2165 (2009/08/14)
(Chemical Presented) H bonds make the catalyst! A single hydrogen bond between ligands coordinated to a rhodium center is critical for the formation of pure supramolecular catalyst for asymmmetric hydrogenation reactions. The ester group of the amidite ligand (see scheme) also forms a hydrogen bond with the coordinated substrate. Use of the herecomplex afforded the highest enantioselectivity reported to date for the hydrogenation of several ester substrates.
Nitro as a novel zinc-binding group in the inhibition of carboxypeptidase A
Wang, Si-Hong,Wang, Shou-Feng,Xuan, Wei,Zeng, Zong-Hao,Jin, Jing-Yi,Ma, Jie,Tian, Guan Rong
, p. 3596 - 3601 (2008/12/20)
2-Substituted 3-nitropropanoic acids were designed and synthesized as inhibitors against carboxypeptidase A (CPA). (R)-2-Benzyl- 3-nitropropanoic acid showed a potent inhibition against CPA (Ki = 0.15 μM). X-ray crystallography discloses that t
Cleavage of β-lactone ring by serine protease. Mechanistic implications
Kim, Dong H.,Park, Jeong-il,Chung, Sang J.,Park, Jung Dae,Park, No-Kyung,Han, Jong Hoon
, p. 2553 - 2560 (2007/10/03)
Both enantiomers of 3-benzyl-2-oxetanone (1) were found to be slowly hydrolyzed substrates of α-chymotrypsin having kcat values of 0.134±0.008 and 0.105±0.004 min-1 for (R)-1 and (S)-1, respectively, revealing that α-CT is virtually unable to differentiate the enantiomers in the hydrolysis of 1. The initial step to form the acyl-enzyme intermediate by the attack of Ser-195 hydroxyl on the β-lactone ring at the 2-position in the hydrolysis reaction may not be enzymatically driven, but the relief of high ring strain energy of β-lactone may constitute a major driving force. The deacylation step is also attenuated, which is possibly due to the hydrogen bond that would be formed between the imidazole nitrogen of His-57 and the hydroxyl group generated during the acylation in the case of (R)-1, but in the α-CT catalyzed hydrolysis of (S)-1 the imidazole nitrogen may form a hydrogen bond with the ester carbonyl oxygen.
A New Approach to Enantiomerically Pure β-Lactams from α-Amino Acids by Applying the Isonitrile-Nitrile Rearrangement
Haaf, Klaus,Ruechardt, Christoph
, p. 635 - 638 (2007/10/02)
(S)-Phenylalanine (1) was converted into (S)-3-benzyl-2-azetidinone (8b) by a multistep reaction sequence.The key step of this approach is a stereospecific isonitrile-nitrile rearrangement ( 3 -> 4) by flash pyrolysis, which may be performed in 20-g batch
