Highly enantioselective synthesis of alpha-alkyl-alanines via the catalytic phase-transfer alkylation of 2-naphthyl aldimine tert-butyl ester by using O(9)-allyl-N(1)-2',3',4'-trifluorobenzylhydrocinchonidinium bromide.
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.
Jew
Sang-sup
SS
Research Institute of Pharmaceutical Science and College of Pharmacy, Seoul National University, Korea. ssjew@plaza.snu.ac.kr
Jeong
Byeong-Seon
BS
Lee
Jeong-Hee
JH
Yoo
Mi-Sook
MS
Lee
Yeon-Ju
YJ
Park
Boon-saeng
BS
Kim
Myoung Goo
MG
Park
Hyeung-geun
HG