Enantiomerically pure (S)-2-chloropropionic acid and several related compounds can be prepared from amino acids via diazotization. [6] In presence of a base halohydrins undergo internal S N 2 reaction to form epoxides. Industrially, the base is calcium hydroxide, whereas in the laboratory, potassium hydroxide is often used.

1999年7月30日 · Halohydrins such as (S)-2,3-dichloro-1-propanol (E>100) and (S)-2-chloro-1-phenylethanol (E=73) were obtained with an enantiomeric excess of higher than 99%. This is a novel biocatalytic route for obtaining enantiomerically pure aromatic halohydrins and epoxides.

1978年1月1日 · When racemic halohydrins (I)-(V) were allowed to react with an insufficient amount of (-)-quinine a 1,3-elimination took place leading to the corresponding epoxides (VI)-(X) with an enantiomeric excess in the range 12-35%.

2024年6月16日 · Vicinal halohydrins are key building blocks to produce bioactive molecules and drugs, especially if they can be obtained in enantiomerically pure form. In this study, we present a bi-enzymatic sequence that allows to obtain vic-halohydrins through a photochemoenzymatic olefin hydroxy halogenation followed by a lipase catalysed kinetic ...

2021年4月13日 · Enantiopure vicinal halohydrins (vic-halohydrins) are highly valuable building blocks for the synthesis of many different natural products and pharmaceuticals, and biocatalytic methods for their synthesis have received considerable interest. This review emphasizes the application of biocatalytic approaches as an efficient alternative or ...

2018年2月17日 · Halohydrin dehalogenases (HHDHs, EC 4.5.1.X) are microbial enzymes that catalyze the conversion of vicinal haloalcohols to the corresponding epoxide, a proton and a halide ion. Alternatively, they can accept different anionic nucleophiles such as azide, cyanide, and nitrite, to open the epoxide ring [1].

2000年4月7日 · The synthesis of a new chiral organophosphorus derivatizing agent prepared from (S)-2-anilinomethylpyrrolidine 1 and its successful use in the determination of enantiomeric composition of various halohydrins by 31 P NMR spectroscopy is described.

panol to (R)-ECH (92.3% enantiomeric excess ee) and (R)-epibromohydrin (81.3% ee). For all tested epoxides, except styrene oxide, the (R)-enantiomer was converted first, affording (S)-isomer in 99% ee. Furthermore, the potential for using a single HHDH to enantioselectively produce both enantiomers of ECH was analyzed.

2011年6月2日 · The excellent results and complementary enantioselectivities of the produced halohydrins obtained by using Rhodotorula glutinis CCT 2182 and Geotrichum candidum CCT 1205 in reduction of ethanones 1a-j are remarkable and highlight the potential of such approach to obtain separately the two isomers of the 1,2-aminoalcohols, by reaction of the ...

2020年9月18日 · We describe a two-step multienzymatic reduction of a series of α-halo -alkyl tetrasubstituted cyclic enones, affording β halohydrins with three contiguous stereogenic centers, in good yield and with a high stereoselectivity.