title: Polymer-supported Cinchona alkaloid-derived ammonium salts as recoverable phase-transfer catalysts for the asymmetric synthesis of alpha-amino acids.
abstract: Alkaloids such as cinchonidine, quinine and N-methylephedrine have been N-alkylated using polymeric benzyl halides or co-polymerized and then N-alkylated, thus affording a series of polymer-supported chiral ammonium salts which have been employed as phase-transfer catalysts in the asymmetric benzylation of an N-(diphenylmethylene)glycine ester. These new polymeric catalysts can be easily recovered by simple filtration after the reaction and reused. The best ee's were achieved when Merrifield resin-anchored cinchonidinium ammonium salts were employed.
authors.affiliation: Departamento de Química Orgánica and Instituto de Síntesis Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain.
authors.forename: Rafael
authors.initials: R
authors.lastname: Chinchilla
authors.forename: Patricia
authors.initials: P
authors.lastname: Mazón
authors.forename: Carmen
authors.initials: C
authors.lastname: Nájera
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D001593:Benzyl Compounds / Q000737:chemistry; D002384:Catalysis; D002929:Cinchona / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D011108:Polymers / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000470:Alkaloids; D000596:Amino Acids; D001593:Benzyl Compounds; D011108:Polymers; D000644:Quaternary Ammonium Compounds; C038682:benzyl bromide