title: Efficient resolution of racemic N-benzyl beta3-amino acids by iterative liquid-liquid extraction with a chiral (salen)cobalt(III) complex as enantioselective selector.
abstract: The efficient (up to 93% ee) resolution of racemic N-benzyl beta(3)-amino acids has been achieved by an iterative (two cycle) liquid-liquid extraction process using a lipophilic chiral (salen)cobalt(III) complex [Co(III)(1)(OAc)]. As a result of the resolution by extraction, one enantiomer of the N-benzyl beta(3)-amino acid predominated in the aqueous phase, while the other enantiomer was driven into the organic phase by complexation to cobalt. The complexed amino acid was then quantitatively released into an aqueous phase, by a reductive (Co(III)--> Co(II)) counter-extraction using l-ascorbic acid. The reductive cleavage allowed for the recovery of the cobalt(II) selector in up to 90% yield (easily re-oxidable to Co(III) with air/AcOH).
authors.affiliation: Dipartimento di Chimica Organica e Industriale, Centro di Eccellenza C.I.S.I., Università degli Studi di Milano, Via G. Venezian, 21, 20133, Milano, Italy. cesare.gennari@unimi.it.
authors.forename: Pawel
authors.initials: P
authors.lastname: Dzygiel
authors.forename: Chiara
authors.initials: C
authors.lastname: Monti
authors.forename: Umberto
authors.initials: U
authors.lastname: Piarulli
authors.forename: Cesare
authors.initials: C
authors.lastname: Gennari
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002623:Chemistry Techniques, Analytical; D003035:Cobalt / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D044367:Phase Transition; D012995:Solubility; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D009942:Organometallic Compounds; D003035:Cobalt