Efficient general asymmetric syntheses of 3-substituted 1(3H)-isobenzofuranones in very high enantiomeric excess

1996 ◽  
Vol 37 (13) ◽  
pp. 2205-2208 ◽  
Author(s):  
P.Veeraraghavan Ramachandran ◽  
Guang-Ming Chen ◽  
Herbert C. Brown
Keyword(s):  
Enantiomeric Excess ◽  
Asymmetric Syntheses ◽  
Substituted 1 ◽  
Very High

Total asymmetric syntheses of (1S,2S)-norcoronamic acid, and of (1R,2R)- and (1S,2S)-coronamic acids from the diastereoselective cyclization of 2-(N-benzylideneamino)-4-chlorobutyronitriles

1994 ◽  
Vol 72 (5) ◽  
pp. 1312-1327 ◽  
Author(s):  
Anne Gaucher ◽  
Jean Ollivier ◽  
Jacqueline Marguerite ◽  
Renée Paugam ◽  
Jacques Salaün
Keyword(s):  
Acid Hydrolysis ◽  
Butyl Acetate ◽  
Molecular Mechanic ◽  
Enantiomeric Excess ◽  
Optically Active ◽  
Chiral Auxiliary ◽  
Enantioselective Hydrolysis ◽  
Asymmetric Syntheses ◽  
Methyl Propionate ◽  
Stereogenic Centers

(3R)-2-(N-Benzylideneamino)-4-chloro-3-methylbutyronitrile 3, prepared from the commercially available methyl (2S)-3-hydroxy-2-methyl propionate 5 (96% ee), readily underwent potassium carbonate induced cyclization to provide, after acid hydrolysis (6 N HCl) and chromatography, the (1S,2S)-norcoronamic acid 1a with 88% diastereoselectivity and > 95% enantiomeric excess. From (2R)-2-(hydroxymethyl)butyl acetate 23 (> 88% ee) obtained by enzymatic enantioselective hydrolysis with lipase PS, was prepared the (3S)-2-(N-benzylideneamino)-3-(chloromethyl)valeronitrile 29, which after base-induced cyclization (K2CO3) and acid (6 N HCl) or basic (0.8 N NaOH) hydrolysis led to the non-natural (1R,2R)-coronamic acid 18 (> 88% ee). Also from this same acetate (2R)-23 was prepared the (3R)-3-(chloromethyl)-2-[(diphenylmethylene)amino]pentanenitrile 37, which provided the (1S,2S)-coronamic acid 17 (> 88% ee) after base-induced cyclization (K2CO3 or LDA) and acid hydrolysis (6 N HCl). It is noteworthy that these short synthetic sequences, which do not require any expensive chiral auxiliary or optically active precursors, do not alter the enantiomeric purity of the stereogenic centers of these 2,3-methanoamino acids. However, the E diastereoselectivity of these cyclizations was not improved by using bulky N-(diphenylmethylene)amino substituent, contrary to results of some molecular mechanic calculations (MAD).

scholarly journals Discovery and molecular and biocatalytic properties of hydroxynitrile lyase from an invasive millipede,Chamberlinius hualienensis

2015 ◽  
Vol 112 (34) ◽  
pp. 10605-10610 ◽  
Author(s):  
Mohammad Dadashipour ◽  
Yuko Ishida ◽  
Kazunori Yamamoto ◽  
Yasuhisa Asano
Keyword(s):  
Specific Activity ◽  
Enantiomeric Excess ◽  
High Specific Activity ◽  
Potassium Cyanide ◽  
Aromatic Aldehydes ◽  
Building Blocks ◽  
Industrial Biotechnology ◽  
Hydroxynitrile Lyase ◽  
Wide Range ◽  
Very High

Hydroxynitrile lyase (HNL) catalyzes the degradation of cyanohydrins and causes the release of hydrogen cyanide (cyanogenesis). HNL can enantioselectively produce cyanohydrins, which are valuable building blocks for the synthesis of fine chemicals and pharmaceuticals, and is used as an important biocatalyst in industrial biotechnology. Currently, HNLs are isolated from plants and bacteria. Because industrial biotechnology requires more efficient and stable enzymes for sustainable development, we must continuously explore other potential enzyme sources for the desired HNLs. Despite the abundance of cyanogenic millipedes in the world, there has been no precise study of the HNLs from these arthropods. Here we report the isolation of HNL from the cyanide-emitting invasive millipedeChamberlinius hualienensis, along with its molecular properties and application in biocatalysis. The purified enzyme displays a very high specific activity in the synthesis of mandelonitrile. It is a glycosylated homodimer protein and shows no apparent sequence identity or homology with proteins in the known databases. It shows biocatalytic activity for the condensation of various aromatic aldehydes with potassium cyanide to produce cyanohydrins and has high stability over a wide range of temperatures and pH values. It catalyzes the synthesis of (R)-mandelonitrile from benzaldehyde with a 99% enantiomeric excess, without using any organic solvents. Arthropod fauna comprise 80% of terrestrial animals. We propose that these animals can be valuable resources for exploring not only HNLs but also diverse, efficient, and stable biocatalysts in industrial biotechnology.

Synthesis of optically active l-acyl-2-O-alkyl-sn-glycero-3-phosphocholine via 1-O-benzyl-sn-glycerol 3-arenesulfonate

1990 ◽  
Vol 68 (1) ◽  
pp. 360-365 ◽  
Author(s):  
Shaukat Ali ◽  
Robert Bittman
Keyword(s):  
Benzyl Alcohol ◽  
Alkyl Group ◽  
Boron Trifluoride ◽  
Enantiomeric Excess ◽  
Boron Trifluoride Etherate ◽  
Optically Active ◽  
Epoxide Ring ◽  
Phospholipid Synthesis ◽  
Tert Butyl ◽  
Very High

A stereocontrolled route to 1-palmitoyl-2-O-hexadecyl-sn-glycero-3-phosphocholine from (R)-glycidyl tosylate is described. This method gives very high enantioselectivity (93–96% enantiomeric excess) and can be used to prepare 3-acyl-2-O-alkyl-sn-glycero-1-phosphocholines from (S)-glycidyl tosylate. The key step is the preparation of 1-O-benzyl-sn-glycerol 3-tosylate by the boron trifluoride etherate catalyzed regio- and stereo-specific opening of the epoxide ring with excess benzyl alcohol. The alkyl group is introduced using alkyl trifluoromethanesulfonate in the presence of excess 2,6-di-tert-butyl-4-methylpyridine. Debenzylation gives 2-O-alkyl-sn-glycerol 3-arenesulfonate, which is acylated and then converted into the phosphocholine. The use of chiral glycidyl derivatives as starting materials for the synthesis of glycerophospholipids is discussed.Key words: acylalkylglycerophospholipids, phospholipid synthesis, glycidyl derivatives in phospholipid synthesis, epoxides as precursors of phospholipids.

scholarly journals Enantiomeric Tartaric Acid Production Using cis-Epoxysuccinate Hydrolase: History and Perspectives

Molecules ◽  
2019 ◽  
Vol 24 (5) ◽  
pp. 903 ◽  
Author(s):  
Jinsong Xuan ◽  
Yingang Feng
Keyword(s):  
Tartaric Acid ◽  
Acid Production ◽  
Enantiomeric Excess ◽  
Enantiomeric Purity ◽  
Enantioselective Synthesis ◽  
Future Research ◽  
Tartaric Acids ◽  
Catalytic Mechanisms ◽  
Very High ◽  
Hydrophilic Molecule

Tartaric acid is an important chiral chemical building block with broad industrial and scientific applications. The enantioselective synthesis of l(+)- and d(−)-tartaric acids has been successfully achieved using bacteria presenting cis-epoxysuccinate hydrolase (CESH) activity, while the catalytic mechanisms of CESHs were not elucidated clearly until very recently. As biocatalysts, CESHs are unique epoxide hydrolases because their substrate is a small, mirror-symmetric, highly hydrophilic molecule, and their products show very high enantiomeric purity with nearly 100% enantiomeric excess. In this paper, we review over forty years of the history, process and mechanism studies of CESHs as well as our perspective on the future research and applications of CESH in enantiomeric tartaric acid production.

On diastereomeric perturbations

2000 ◽  
Vol 78 (6) ◽  
pp. 816-828 ◽  
Author(s):  
Christian Girard ◽  
Henri B Kagan
Keyword(s):  
Asymmetric Synthesis ◽  
High Selectivity ◽  
Enantiomeric Excess ◽  
Chemical Properties ◽  
Nonlinear Effects ◽  
Minimum Condition ◽  
Living Matter ◽  
Physico Chemical ◽  
The Common ◽  
Very High

For more than a century, organic chemists have been playing in Nature's laboratory. Their first goal was to understand the organization of atoms in the living matter and then to reproduce it by synthesis. This quest gave rise to several efficient techniques to synthesise molecules; many of them still in use nowadays, as such or with little modifications. Even at the beginning of this journey, the chemists discovered that their methods were far from being as efficient as the ones used by Nature to produce substances. The natural molecules were chiral and there was even an enantiomer that was produced over the other;a lesson of perfection. This was another challenge for the chemists and they succeeded by first developing techniques to separate enantiomers and more recently reagents and reactions to produce only the desired stereoisomer. Asymmetric synthesis uses chiral auxiliaries, reagents or catalysts to create chirality into the desired compound. The common perception, as a minimum condition, was that the chiral substance used to perform such a transformation has to be of the highest enantiomeric purity to obtain a very high selectivity. The relation between the enantiomeric excesses of the chiral substance and the product was suggested to be linear. But there were a lot of surprises left in the laboratory. Who would have thought that an impure substance could give an enantiomeric excess in the product higher than its own purity? The molecules are acting in different ways in solution. Self-organization and aggregation can arise depending on the structure of the substance or its environment. Such phenomenon can generate deviations to the awaited behaviour of the molecules that can be observed in many cases. This article tries to present some examples of the historical reports of such peculiar behaviours, their influence on physico-chemical properties and the final discovery of the now well-known nonlinear effects in asymmetric synthesis.Key words: asymmetric synthesis, diastereomeric interactions, nonlinear effects.

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