title: Asymmetric PTC C-alkylation catalyzed by chiral derivatives of tartaric acid and aminophenols. Synthesis Of (R)- and (S)-alpha-methyl amino acids
abstract: A new type of efficient chiral catalyst has been elaborated for asymmetric C-alkylation of CH acids under PTC conditions. Sodium alkoxides formed from chiral derivatives of tartaric acid and aminophenols (TADDOL's 2a-e and NOBIN's 3a-h) can be used as chiral catalysts in the enantioselective alkylation, as exemplified by the reaction of Schiff's bases 1a-e derived from alanine esters and benzaldehydes with active alkyl halides. Acid-catalyzed hydrolysis of the products formed in the reaction afforded (R)-alpha-methylphenylalanine, (R)-alpha-naphthylmethylalanine, and (R)-alpha-allylalanine in 61-93% yields and with ee 69-93%. The procedure could be successfully scaled up to 6 g of substrate 1b. When (S,S)-TADDOL or (R)-NOBIN are used, the (S)-amino acids are formed. A mechanism rationalizing the observed features of the reaction has been suggested.
authors.affiliation: A. N. Nesmeyanov Institute of Organo-Element Compounds, Russian Academy of Sciences, 117813, Moscow, Vavilov 28, Russian Federation, Higher Chemical College, Russian Academy of Sciences, 125820 Moscow, Russian Federation, Department of Chemistry, U.
authors.initials: YN
authors.lastname: Belokon
authors.initials: KA
authors.lastname: Kochetkov
authors.initials: TD
authors.lastname: Churkina
authors.initials: NS
authors.lastname: Ikonnikov
authors.initials: AA
authors.lastname: Chesnokov
authors.initials: OV
authors.lastname: Larionov
authors.initials: I
authors.lastname: Singh
authors.initials: VS
authors.lastname: Parmar
authors.initials: S
authors.lastname: Vyskocil
authors.initials: HB
authors.lastname: Kagan