Synthesis and application of dimeric Cinchona alkaloid phase-transfer catalysts: alpha,alpha '-bis[O(9)-allylcinchonidinium]-o, m, or p-xylene dibromide
Ss. Jew et al., Synthesis and application of dimeric Cinchona alkaloid phase-transfer catalysts: alpha,alpha '-bis[O(9)-allylcinchonidinium]-o, m, or p-xylene dibromide, CHEM COMMUN, (14), 2001, pp. 1244-1245
A dimeric Cinchona alkaloid ammonium salt, alpha,alpha'-bis[ O( 9) allylcin
chonidinium]- m-xylene dibromide 4, has been developed as a new efficient p
hase-transfer catalyst; the catalytic enantioselective alkylation of N-(dip
henylmethylene)glycine tert-butyl ester using 4 provided 7 in a high enanti
omeric excess (90-99% ee).