58917-25-2Relevant academic research and scientific papers
Highly Selective Asymmetric Intramolecular Selenocyclisation
Nishibayashi, Yoshiaki,Srivastava, Sanjay Kumar,Takada, Hiroya,Fukuzawa, Shin-ichi,Uemura, Sakae
, p. 2321 - 2322 (1995)
Asymmetric intramolecular selenocyclisation of alkenoic acids, alkenols and olefinic urethanes using chiral ferrocenylselenenyl cations proceeds smoothly to give the corresponding lactones, cyclic ethers and nitrogen-heterocyclic compounds, respectively, in moderate yields with very high diastereoselectivities.
A FACILE SYNTHESIS OF OPTICALLY PURE VALEROLACTONE AND β-HYDROXY VALEROLACTONE FROM A COMMON SUGAR-DERIVED PRECURSOR
Papageorgiou, Christos,Benezra, Claude
, p. 6041 - 6044 (1984)
Both title compounds were obtained in four steps from 2R, 3R-dihydroxy-4R-valerolactone 5 readily available from D-ribonolactone.
Carboxyl Group-Directed Iridium-Catalyzed Enantioselective Hydrogenation of Aliphatic ?-Ketoacids
Li, Mao-Lin,Li, Yao,Li, Yi-Hao,Pan, Jia-Bin,Song, Song,Zhou, Qi-Lin,Zhu, Shou-Fei
, p. 10032 - 10039 (2020/10/18)
Although the transition metal-catalyzed asymmetric hydrogenation of aromatic ketones has been extensively explored, the enantioselective hydrogenation of aliphatic ketones remains a challenge because chiral catalysts cannot readily discriminate between the re and si faces of these ketones. Herein, we report a carboxyl-directing strategy for the asymmetric hydrogenation of aliphatic ?-ketoacids. With catalysis by iridium complexes bearing chiral spiro phosphino-oxazoline ligands, hydrogenation of aliphatic ?-ketoacids afforded chiral ?-hydroxylacids with high enantioselectivity (up to 99% ee). Mechanistic studies revealed that the carboxyl group of the substrate directs hydrogen transfer and ensures high enantioselectivity. Density functional theory calculations suggested the occurrence of chiral induction involving a hydrogen-hydrogen interaction between a hydride on the iridium atom and the substituent on the oxazoline ring of the ligand, and on the basis of the calculations, we proposed a catalytic cycle involving only Ir(III), which differs from the Ir(III)/Ir(V) catalytic cycle that operates in the hydrogenation of α,β-unsaturated carboxylic acids.
Iridium-Catalyzed Asymmetric Hydrogenation of ?- A nd ?-Ketoacids for Enantioselective Synthesis of ?- A nd ?-Lactones
Hua, Yun-Yu,Bin, Huai-Yu,Wei, Tao,Cheng, Hou-An,Lin, Zu-Peng,Fu, Xing-Feng,Li, Yuan-Qiang,Xie, Jian-Hua,Yan, Pu-Cha,Zhou, Qi-Lin
supporting information, p. 818 - 822 (2020/02/15)
A highly efficient asymmetric hydrogenation of ?- A nd ?-ketoacids was developed by using a chiral spiro iridium catalyst (S)-1a, affording the optically active ?- A nd ?-hydroxy acids/lactones in high yields with excellent enantioselectivities (up to >99% ee) and turnover numbers (TON up to 100000). This protocol provides an efficient and practical method for enantioselective synthesis of Ezetimibe.
Chiron approach towards optically pure γ-valerolactone from alanine
Datrika, Rajender,Kallam, Srinivasa Reddy,Katta, Rambabu,Siddaiah, Vidavalur,Pratap
, p. 2801 - 2808 (2018/12/04)
A concise synthesis of both enantiomers of γ-valerolactone has been developed from commercially available Alanine. The key steps in the synthesis of these γ-Lactones are DIBAL-H reduction of ester (9) followed by in situ Wittig reaction with EtO2CCH = PPh3 ylide (13) (Z/E = 1: 3.5) and one pot lactonization triggered by deprotection of O-TBS ether (14).
Facile Synthesis of Optically-Active Γ-Valerolactone from Levulinic Acid and Its Esters Using a Heterogeneous Enantio-Selective Catalyst
Osawa, Tsutomu,Tanabe, Yuya
, p. 824 - 830 (2018/01/27)
Abstract: Optically-active γ-valerolactone was synthesized by the enantio-selective hydrogenations of levulinic acid and its esters. A tartaric acid-NaBr-modified nickel catalyst produced the optically-active γ-valerolactone with a 60% enantiomeric excess (ee), almost quantitative conversion and chemoselectivity. The synthesis of the optically-active γ-valerolactone using the enantio-selective heterogeneous catalyst would be promising for the large-scale industrial production from levulinic acid and its esters, which can be obtained by the acid-catalyzed dehydration of cellulosic fraction of biomass. Graphical Abstract: [Figure not available: see fulltext.].
Combination of Metal-Catalyzed Cycloisomerizations and Biocatalysis in Aqueous Media: Asymmetric Construction of Chiral Alcohols, Lactones, and γ-Hydroxy-Carbonyl Compounds
Rodríguez-álvarez, María J.,Ríos-Lombardía, Nicolás,Schumacher, S?ren,Pérez-Iglesias, David,Morís, Francisco,Cadierno, Victorio,García-álvarez, Joaquín,González-Sabín, Javier
, p. 7753 - 7759 (2017/11/10)
The combination of the metal-catalyzed cycloisomerization of alkynes containing a tethered nucleophile as substituent in aqueous media (followed by the spontaneous hydrolysis, hydroalkoxylation, or aminolysis of the transiently formed five-membered heterocycles) with the subsequent enantioselective ketone bioreduction (mediated by KREDs) has been achieved. The overall transformations, which formally involve a three-step one-pot reaction, provide a variety of enantiopure valuable molecules (e.g., 1,4-diols, lactones, and γ-hydroxy-carbonyl compounds (carboxylic acids, esters, and amides)) with high conversions and enantioselectivities and under mild reaction conditions, disclosing the concept of integrated metal-catalyzed cycloisomerizations of alkynes and enzymatic catalysis in water.
Sodium Ion as the Most Essential and Effective Element for the Enantio-Differentiating Hydrogenation of Prochiral Ketones over Tartaric Acid Modified Ni Catalyst
Osawa, Tsutomu,Tanabe, Yuya,Fujiwara, Manabu
, p. 686 - 692 (2017/03/08)
Abstract: In order to investigate the role of metal ions on a tartaric acid modified nickel catalyst, the enantio-differentiating hydrogenations of methyl acetoacetate and methyl levulinate were carried out. The effects of the addition of 17 metal salts of acetic acid on the enantio-selectivity and the hydrogenation rate were investigated during the hydrogenation of methyl acetoacetate. Among the examined metal salts, the addition of NaBr caused the great increase in the enantio-selectivity and the hydrogenation rate during the hydrogenations of both methyl acetoacetate and methyl levulinate. Based on the strength of the interaction between the metal salts of tartaric acid and the substrate, the sodium salts would have the strongest interaction with the substrate, hence, this would be attributed to the highest enantio-selectivity and hydrogenation rate for the sodium salts of tartaric acid. Graphical Abstract: [Figure not available: see fulltext.]
Stability of gamma-valerolactone under neutral, acidic, and basic conditions
Wong, Claire Yuet Yan,Choi, Alex Wing-Tat,Lui, Matthew Y.,Fridrich, Bálint,Horváth, Attila K.,Mika, László T.,Horváth, István T.
, p. 423 - 429 (2017/02/23)
Dry gamma-valerolactone (GVL) is stable for several weeks at 150?°C and its thermal decomposition only proceeds in the presence of appropriate catalysts. Since GVL does not react with water up to 60?°C for several weeks, it could be used as a green solvent at mild conditions. At higher temperatures, GVL reacts with water to form 4-hydroxyvaleric acid (4-HVA) and reaches the equilibrium in a few days at 100?°C. Aqueous solutions of acids (HCl and H2SO4) catalyze the ring opening of GVL even at room temperature, which leads to the establishment of an equilibrium between GVL, water, and 4-HVA. Although the 4-HVA concentration would be below 4?mol% in the presence of acids, it could be higher than the concentration of a reagent or a catalyst precursor, not to mention a catalytically active species. The latter could be especially worrisome as 4-HVA could be an excellent bi- or even a tri-dentate ligand for transition metals. Aqueous solution of bases (NaOH and NH4OH) also catalyzes the reversible ring opening of GVL. While in the case of NaOH, the product is the sodium salt of 4-hydroxyvalerate, the reversible reaction of GVL, with NH4OH results in the formation of 4-hydroxyvaleric amide. The reversible ring opening of (S)-GVL in the presence of HCl or NaOH has no effect on the stability of the chiral center.
Stereoselective synthesis of (R)-(?) and (S)-(+)-phoracantholide I from (R)-(+)-γ-valerolactone
Datrika, Rajender,Kallam, Srinivasa Reddy,Khobare, Sandip R.,Gajare, Vikas S.,Kommi, Muralikrishna,Rama Mohan,Siddaiah, Vidavalur,Pratap
, p. 603 - 607 (2016/07/11)
A concise total synthesis of (R)-(?)-phoracantholide I 1 and (S)-(+)-phoracantholide I 2 has been developed from (R)-(+)-γ-valerolactone 6. The key steps in the synthesis of these macrolides involved enzymatic reduction of Levulinic ester 4 by asymmetric dehydrogenase, Z-selective Wittig reaction of (4-carboxybutyl)triphenylphosphonium ylide 11 with lactol 7, and cyclization of seco-acid 8 using either a Yamaguchi lactonization protocol or a Mitsunobu protocol to afford (R)-(?)-phoracantholide I and (S)-(+)-phoracantholide I respectively.
