FLUORINATED AMINO-ACIDS - THE MECHANISM OF THE ALPHA-BROMO-GAMMA-FLUORO-ALPHA,BETA-UNSATURATED ESTER AMINATION WITH AMMONIA IN DMSO

This work examines the effect of a gamma-fluorine substituent on the conversion of an alpha,beta-unsaturated alpha-bromobutenoate to a trans beta,gamma-unsaturated gamma-fluoro-alpha-amino acid, by the action of NH3 in DMSO. Employing bromo ester 6 as the substrate, product isolation-identification...

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Bibliographic Details
Published inBulletin de la Société chimique de France Vol. 129; no. 5; pp. 529 - 540
Main Authors LASKOVICS, FM, LEBORGNE, JF, PIRIOU, F, WOLF, E
Format Journal Article
LanguageEnglish
Published PARIS CEDEX 15 Elsevier 01.01.1992
Subjects
Biochemistry & Molecular Biology
Chemistry
Chemistry, Multidisciplinary
Chemistry, Organic
Life Sciences & Biomedicine
Physical Sciences
Science & Technology
MONOAMINE-OXIDASE
VINYL FLUORIDE
FLUORINATED AMINO ACID
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Summary:This work examines the effect of a gamma-fluorine substituent on the conversion of an alpha,beta-unsaturated alpha-bromobutenoate to a trans beta,gamma-unsaturated gamma-fluoro-alpha-amino acid, by the action of NH3 in DMSO. Employing bromo ester 6 as the substrate, product isolation-identification studies, a kinetic analysis and deuterium labelling studies show that the gamma-fluorine substituent increases the propensity for 1,4-addition of NH3 and decreases the kinetic acidity of the gamma-proton. These electronic effects enhance the formation of aziridines 10 and 11 at the expense of amino ester 8. Arguments are presented that support the reversible 1,4-addition of NH3 to 6, and the irreversible removal of the gamma-proton from 6, as being the rate-determining steps for the formation of the aziridines and 8, respectively. Furthermore, these studies support a gauche fluorine-aromatic ring arrangement as the most favored rotamer of 6 during its regio-specific conversion to trans fluoro-olefin 8.
ISSN:0037-8968