- METHOD FOR PRODUCING OPTICALLY ACTIVE CARBOXYLIC ACID ESTER
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Provided is a method for producing an optically active carboxylic acid ester at a high yield and with high enantioselectivity using dynamic kinetic resolution, said optically active carboxylic acid ester having an α-nitrogen substituent. This method for producing an optically active carboxylic acid ester includes a step in which racemic carboxylic acid represented by formula (a) and a specific alcohol or phenol derivative are reacted in a polar solvent having a dipole moment of at least 3.5 in the presence of an acid anhydride and an asymmetric catalyst, one enantiomer of the racemic carboxylic acid is selectively esterified, and the other enantiomer is racemized. In formula (a), Ra1 represents a nitrogen-containing heteroaromatic ring group bonded to an assymetric carbon via a nitrogen atom constituting a ring, and Ra2 is an organic group.
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Paragraph 0770; 0773; 07740775-0788
(2017/01/26)
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- Nonenzymatic dynamic kinetic resolution of α-(arylthio)- and α-(alkylthio)alkanoic acids
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Dynamic solution: The title acids undergo dynamic kinetic resolution during an enantioselective esterification catalyzed by (S)-homobenzotetramisole ((S)-HBTM; see scheme). This method extends the scope of the carboxylic acid derivatives that are amenable to the nonenzymatic version of this transformation. Copyright
- Yang, Xing,Birman, Vladimir B.
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supporting information; experimental part
p. 5553 - 5555
(2011/07/09)
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- Kinetic resolution of α-substituted alkanoic acids promoted by homobenzotetramisole
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A new method for catalytic nonenzymatic kinetic resolution of α-substituted alkanoic acids has been developed, which relies on their activation with DCC followed by enantioselective alcoholysis of the intermediate symm-anhydrides in the presence of the amidine-based catalyst homobenzotetramisole (HBTM). Moderate to excellent selectivity factors (s=5-96) have been obtained in the case of several classes of substrates, namely, α-aryl-, α-aryloxy/alkoxy-, α-halo-, α-azido-, and α-phthalimido-alkanoic acids. Under similar conditions, α-(arylthio/alkylthio)-alkanoic acids undergo dynamic kinetic resolution providing corresponding esters in up to 92 % ee and up to 93 % yield. Copyright
- Yang, Xing,Birman, Vladimir B.
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supporting information; experimental part
p. 11296 - 11304
(2011/10/19)
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