title: Asymmetric synthesis of α-amino acids via homologation of Ni(II) complexes of glycine Schiff bases; Part 1: alkyl halide alkylations.
abstract: Alkylations of chiral or achiral Ni(II) complexes of glycine Schiff bases constitute a landmark in the development of practical methodology for asymmetric synthesis of α-amino acids. Straightforward, easy preparation as well as high reactivity of these Ni(II) complexes render them ready available and inexpensive glycine equivalents for preparing a wide variety of α-amino acids, in particular on a relatively large scale. In the case of Ni(II) complexes containing benzylproline moiety as a chiral auxiliary, their alkylation proceeds with high thermodynamically controlled diastereoselectivity. Similar type of Ni(II) complexes derived from alanine can also be used for alkylation providing convenient access to quaternary, α,α-disubstituted α-amino acids. Achiral type of Ni(II) complexes can be prepared from picolinic acid or via recently developed modular approach using simple secondary or primary amines. These Ni(II) complexes can be easily mono/bis-alkylated under homogeneous or phase-transfer catalysis conditions. Origin of diastereo-/enantioselectivity in the alkylations reactions, aspects of practicality, generality and limitations of this methodology is critically discussed.
authors.affiliation: Department of Organic Chemistry I, Faculty of Chemistry, University of the Basque Country UPV/EHU, 20018, San Sebastián, Spain.
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Sorochinsky
authors.forename: José Luis
authors.initials: JL
authors.lastname: Aceña
authors.forename: Hiroki
authors.initials: H
authors.lastname: Moriwaki
authors.forename: Tatsunori
authors.initials: T
authors.lastname: Sato
authors.forename: Vadim A
authors.initials: VA
authors.lastname: Soloshonok
mesh_terms: D000478:Alkylation; D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D005998:Glycine / Q000737:chemistry*; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D012545:Schiff Bases / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D006846:Hydrocarbons, Halogenated; D009942:Organometallic Compounds; D012545:Schiff Bases; D009532:Nickel; D005998:Glycine