摘要:
Process for preparing optically active 2-piperazine-carboxylic acid derivatives, particularly S-enantiomer thereof, in high yield and high optical purity on industrial scale. As the optical resolving agents, easily accessible sulfonamides derived from selected optically active amino acids, such as N-tosyl-L-phenylalanine, N-tosyl-D-phenylglycine, N-tosyl-L-alanine or N-tosyl-L-valine, give excellent results. These resolving agents are stable and easily recovered from the reaction mixture and reused. Resolved 2-piperazinecarboxylic acid derivatives are preferably isolated as 4-t-butoxycarbonyl (Boc) derivatives. Diastereomeric salts (an example being shown below) formed as the intermediates of resolution are novel. ##STR1## �In the formula "Ar" stands for a phenyl or naphthyl group which may be substituted with one to three C1-C6 alkyl groups, halogen atoms, nitro or alkoxy groups; and n=0 or 1.!
摘要:
The present invention provides a novel transition metal complex which catalyzes asymmetric hydrogenation reaction. The present invention also provides a process for the preparation of the foregoing novel complex. The present invention further provides an asymmetric hydrogenation catalyst comprising the foregoing novel complex. The novel transition metal complex is provided, represented by the following general formula (I): ##STR1##
摘要:
An optically active compound represented by the following formula (I): ##STR1## wherein R.sub.1 denotes an alkyl or alkoxy group having 1-18 carbon atoms; R.sub.2 denotes an alkyl group having 1-12 carbon atoms; A denotes ##STR2## X denotes and C* denotes an optically active asymmetric carbon atom. The optically active compound, when included as a component, provides a ferroelectric liquid crystal composition or device showing an improved electro-field response characteristic.
摘要:
A process for producing a carboxylic acid or an ester thereof represented by formula (I): ##STR1## wherein: R represents a hydrogen atom or a lower alkyl group; R.sup.1 represents a lower alkyl group; CH.sub.2 COOR.sup.3, wherein R.sup.3 represents a hydrogen atom or a lower alkyl group; or NHR.sup.4, wherein R.sup.4 represents a formyl group, an acetyl group, a benzoyl group, or a chloroacetyl group, andR.sup.2 represents a hydrogen atom, a lower alkyl group, or a phenyl group,which comprises hydrogenating an unsaturated compound represented by formula (II): ##STR2## wherein R, R.sup.1, and R.sup.2 are as defined above, in the presence of a rhodium or ruthenium complex catalyst having, as a ligand, BICHEP which means 2,2'-bis(dicyclohexylphoshino)-6,6'-dimethyl-1,1'-biphenyl represented by formula (III): ##STR3## is disclosed.
摘要:
An optically active, generally mesomorphic compound represented by the following formula (I): ##STR1## wherein R.sub.1 denotes an alkyl group having 1-18 carbon atoms, R.sub.2 denotes an alkyl group having 1-12 carbon atoms; X denotes a single bond, --O--, ##STR2## Y denotes a single bond, ##STR3## --CH.sub.2 O-- or --OCH.sub.2 --; Z denotes --OCH.sub.2 --, ##STR4## C* denotes an asymmetric carbon atom; k, m and n are respectively 0, 1 or 2 with proviso that k+m+n amounts to 2 or 3; and p is 1 or 2.
摘要:
A novel (-)-optically active piperazine derivative of the formula: ##STR1## (wherein the mark of * indicates an optically active carbon) shows an increased cerebral circulation-improving effect as well as an enhanced safety.
摘要:
A process for the optical resolution of (.+-.)-2-hydroxy-4-phenylbutanoic acid which comprises treating (.+-.)-2-hydroxy-4-phenylbutanoic acid with an optically active 1-(p-tolyl)ethylamine or an optically active N-(2-hydroxy)ethyl-.alpha.-methylbenzylamine as a resolving agent is provided by the present invention.According to the invention, (-)-2-hydroxy-4-phenylbutanoic acid, which is useful as a starting substance for the synthesis of angiotensin converting enzyme-inhibiting pharmaceuticals, can especially be obtained in a highly pure state and in a high yield.
摘要:
(.+-.)-2-Amino-1-butanol and/or (.+-.)-mandelic acid are optically resolved with a high resolution efficiency and high optical purities by preferentially crystallizing out one of the pair of less soluble enantiomeric salts (or optical antipodes), namely (+)-2-amino-1-butanol-(+)-mandelic acid salt and (-)-2-amino-1-butanol-(-)-mandelic acid salt.
摘要:
An optically active compound of the formula (I) according to claim 1 is suitable as a component for a liquid crystal composition providing improved response speed. The optically active compound of the formula (I) is characterized by having a fluorine-substituted optically active cite and ##STR1## group connected by 1-6 methylene groups. The above liquid crystal composition is useful as an element of a liquid crystal device and a display apparatus providing a good display characteristics.
摘要:
A liquid crystal composition, comprising: at least one optically active mesomorphic compound having an asymmetric carbon atom to which a fluorine atom is directly bonded.