A trimeric Cinchona alkaloid ammonium salt, alpha,alpha',alpha" -tris[O(9)-allylcinchonidinium]mesitylene tribromide has been prepared as a novel phase-transfer catalyst. The catalytic enantioselective alkylation of N-(diphenylmethylene)glycine tert-butyl ester using the trimer catalyst showed high enantioselectivity (90-97% ee). (C) 2001 Elsevier Science Ltd. All rights reserved.
The synthesis of the first calixarene-based chiralphase-transfercatalysts derived from cinchona alkaloids has been achieved in two steps from p-tert-butylcalix[4]arene. The catalytic efficiency of the chiral calix[4]arenes 3a–c was evaluated by carrying out the phase-transfer alkylation of N-(diphenylmethylene)glycine ethyl ester with benzyl bromide. Various factors that affect the chemical yield
Absolute Conformation and Configuration of (2S, 3S)-3-Acetoxy-5-(dimethylaminoethyl)-2-(4-methoxyphenyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one Chloride (Dilthiazem Hydrochloride)
Resolution of racemic cis-3-(2-aminophenylthio)-2-hydroxy-3-(4-methoxyphenyl) propionic acid (2) via the cinchonidine salt 3, and brucine salt 4, isolation of the calcium salts (+)- and (−)-5, as well as their cyclization to enantiomeric 1,5-benzothiazepines (+)- and (−)-1, are described. X-Ray single-crystal analysis reveals (2S, 3S) absoluteconfiguration of (+)-1 on the basis of tentative comparison of CD