title: Theoretical evidence for pyramidalized bicyclic serine enolates in highly diastereoselective alkylations.
abstract: A new chiral serine equivalent and its enantiomer have been synthesized from (S)- and (R)-N-Boc-serine methyl esters (Boc: tert-butyloxycarbonyl). The use of these compounds as chiral building blocks has been demonstrated in the synthesis of alpha-alkyl alpha-amino acids by diastereoselective potassium enolate alkylation reactions and subsequent acid hydrolyses. Theoretical studies were performed to elucidate the stereochemical outcome of both the formation of five-membered cyclic N,O-acetals and the subsequent alkylation process, which occurs with total retention of configuration. This feature could be explained in terms of the high degree of pyramidalization of enolate intermediates.
authors: Departamento de Química, Universidad de La Rioja, UA-CSIC, 26006 Logroño, Spain.
authors: Carlos
authors: C
authors: Aydillo
authors: Gonzalo
authors: G
authors: Jiménez-Osés
authors: Jesús H
authors: JH
authors: Busto
authors: Jesús M
authors: JM
authors: Peregrina
authors: María M
authors: MM
authors: Zurbano
authors: Alberto
authors: A
authors: Avenoza
mesh_terms: D000080:Acetals / Q000138:chemical synthesis / Q000737:chemistry; D000478:Alkylation; D000596:Amino Acids / Q000138:chemical synthesis / Q000737:chemistry*; D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D004952:Esters / Q000138:chemical synthesis / Q000737:chemistry*; D006868:Hydrolysis; D015394:Molecular Structure; D010080:Oxazoles / Q000138:chemical synthesis / Q000737:chemistry*; D012694:Serine / Q000031:analogs & derivatives / Q000737:chemistry; D013237:Stereoisomerism
chemical_list: D000080:Acetals; D000596:Amino Acids; D001643:Bridged Bicyclo Compounds; D004952:Esters; D010080:Oxazoles; D012694:Serine; C429009:serine methyl ester