摘要:
The present invention relates to a novel process for the preparation of pantolactone by reaction of hydroxypivalaldehyde cyanohydrin in a phase separation process.
摘要:
The present invention is characterized in that racemic or optically active D- or L-α-glycerophosphoryl choline solids are prepared from liquid type racemic or optically active D- or L-α-glycerophosphoryl choline using an organic solvent. The present invention can produce solids at a high yield more easily through phase transformation rather than a method using a difference in solubility in a solvent, which is an existing method.
摘要:
This invention relates to a method for obtaining optically pure amino acids, including optical resolution and optical conversion. This method significantly shortens the time taken for optical transformation, and enables the repeated use of an organic solution containing a enantioselective receptor, to thereby obtain optically pure amino acids in a simple and remarkably efficient manner, and to enable the very economical mass production of optically pure amino acids.
摘要:
By reacting a β-hydroxy-α-amino acid with sulfuryl fluoride (SO2F2) in the presence of an organic base, it is possible to produce an α-fluoro-β-amino acid of the formula [2]. By using a C8-12 tertiary amine having two or more alkyl groups of C3 or higher, and especially diisopropylethylamine, as the organic base, by-production of quantery ammonium salts is effectively suppressed. By applying the production process of the present invention, it is possible to very easily produce (2R)-3-(dibenzylamino)-2-fluoropropionic acid methyl ester, which is extremely important as a pharmaceutical intermediate, with high positional selectivity even on an industrial scale.
摘要:
There is provided a process for producing an α-substituted ester by reaction of a fluorosulfuric acid ester of α-hydroxyester with a Grignard reagent in the presence of a zinc catalyst. It is newly found that the reaction for production of α-substituted esters, in which the raw reaction substrate is limited to expensive trifluoromethanesulfonic acid esters, can proceed favorably with the use of fluorosulfuric acid esters suitable for mass-production uses. By the use of the fluorosulfuric acid ester high in optical purity, it is possible to obtain the α-substituted ester with high optical purity upon inversion of the asymmetric carbon configuration. The process of the present invention can solve all of the prior art problems and can be applied for industrial uses.
摘要:
A method for the production of optically active α-alkylcarbonyl compounds with retention of the stereo information of the starting compound. The starting compound used here is a carbonyl compound which has, in the α-position, a leaving group which is substituted by an alkyl group with inversion of the configuration. The substitution of the leaving group is effected with the use of an alkylmagnesium Grignard and a zinc (II) salt or a zinc organyl. The method permits the production of optically active α-alkylcarbonyl compounds at very mild temperatures (for example 0° C.) with the use of starting compounds which are easy to prepare and economical and nontoxic catalysts, it also being possible to achieve a very high yield.
摘要:
Benzyl alcohols having a chiral center at the benzylic carbon can be conveniently racemized by treatment with solid acids which are strongly acidic cation exchange materials. Racemization may be effected generally in the range from 20.degree.-150.degree. C. in aqueous or partly aqueous systems in combination with a water-miscible organic solvent to improve solubility of the alcohol. Similar racemizations may be effected for benzyl ethers and esters. This process is valuable for recycling of unwanted enantiomers obtained in the resolution of racemic mixtures.
摘要:
A novel process for the preparation of racemic allethrolone of the (R,S) configuration comprising heating optically active allethrolone of the (R) configuration or of the (S) configuration or a mixture of the (R) and (S) configurations in non-equimolecular proportions with formic acid to form the formate of racemic allethrolone of (R,S) configuration and hydrolyzing the latter in the presence of an acid or base to obtain racemic (R,S) allethrolone.
摘要:
The present invention provides a process for preparing racemic allethrolone which comprises reacting (-) allethrolone with hydroxylamine to form the corresponding allethrolone.oxime and then hydrolyzing the oxime in water or a mixture of water and an organic solvent miscible with water in the presence of an acid.
摘要:
The present invention relates to a process of separating chiral isomers of chroman compounds, particularly tocopherols and tocotrienols as well as the esters and intermediates thereof. It has been found that this process allows a separation of the desired isomer with a higher yield and enables the use of the non-desired isomers in a very efficient way. Said process is particularly useful when implemented in an industrial process. Furthermore, it has been found that this process allows using isomer mixtures as they result from traditional industrial synthesis.