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Jew SS Jeong BS Lee JH Yoo MS Lee YJ Park BS Kim MG Park HG 《The Journal of organic chemistry》2003,68(11):4514-4516
Systematic investigations to develop an efficient enantioselective synthetic method for alpha-alkyl-alanine by catalytic phase-transfer alkylation were performed. The alkylation of 2-naphthyl aldimine tert-butyl ester, 1E, with RbOH and O(9)-allyl-N-2',3',4'-trifluorobenzylhydrocinchonidinium bromide, 6, at -35 degrees C showed the highest enantioselectivities, up to 96% ee. 相似文献
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Soon Kil Ahn Nam Song Choi Byeong Seon Jeong Kye Kwang Kim Duck Jin Journ Joon Kyum Kim Sang Joon Lee Jung Woo Kim Chung Hong Sang‐Sup Jew 《Journal of heterocyclic chemistry》2000,37(5):1141-1144
A practical semi‐synthetic method of (S)‐7‐(2‐isopropylamino)ethylcamptothecin hydrochloride has been developed. The Mannich reaction of (S)‐7‐methylcamptothecin with isopropylamine hydrochloride in dimethyl sulfoxide as a formaldehyde source gave the desired product in moderate yield. 相似文献
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We reported efficient enantioselective synthetic methodologies for (R)-alpha-alkylcysteines and (S)-alpha-alkylcysteines. The phase-transfer catalytic alkylation of 2-phenyl-2-thiazoline-4-carboxylic acid tert-butyl ester and 2-o-biphenyl-2-thiazoline-4-carboxylic acid tert-butyl ester, in the presence of chiral catalysts (1 or 2), gave the corresponding alkylated products, which could be hydrolyzed to provide (R)-alpha-alkylcysteines (67->99% ee) and (S)-alpha-alkylcysteines (66-88% ee), respectively. 相似文献
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Hyeung-geun ParkByeong-Seon Jeong Mi-Sook YooJeong-Hee Lee Boon-saeng ParkMyoung Goo Kim Sang-sup Jew 《Tetrahedron letters》2003,44(17):3497-3500
A series of cinchona alkaloid-derived dimeric quaternary ammonium salts were prepared as chiral phase-transfer catalysts by the introduction of various functional groups on the phenyl ligand. Among them, the 2-F-substituted derivative 21 showed the highest enantioselectivity in the alkylation of the glycine anion equivalent 1 (97 to >99% ee). 相似文献
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