An Unusual Electronic Effect of an Aromatic-F in Phase-Transfer Catalysts Derived from Cinchona -Alkaloid
2002; American Chemical Society; Volume: 4; Issue: 24 Linguagem: Inglês
10.1021/ol0267679
ISSN1523-7060
AutoresSang‐sup Jew, Mi‐Sook Yoo, Byeong‐Seon Jeong, Il Yeong Park, Hyeung‐geun Park,
Tópico(s)Fluorine in Organic Chemistry
ResumoVarious N-benzylcinchonidinium salts were prepared to study electronic factors in the catalytic enantioselective phase-transfer alkylation of glycine anion equivalent. An ortho-fluoro substituent on the benzyl group in the quaternary ammonium salt dramatically increased the enantioselectivity in the alkylation. O(9)-Allyl-N-2',3',4'-trifluorobenzylhydrocinchonidinium bromide (27), which gave the highest enantioselectivity of the catalysts studied, was used to prepare 12 α-alkylated amino acid derivatives in 94∼>99% ee.
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