Synthese et equilibre thermodynamique des huit 5-O-benzyl-2- (ou 3)- dimethylamino-3 (ou 2)-O-mesyl-α (ou β)-D- (ou ) - furanosides de methyle
摘要:
Regioselectivity of the opening of 2,3-anhydrofuranosides 1 (alpha and beta) and 2 (alpha and beta) by dimethylamine (and by ammonia for 1) has been determined. Thermic stability of the eight corresponding vic-dimethylaminomesylates 11-14 (alpha and beta) in CD3CN and C6D6 has been studied by H-1 NMR : in each case steric hindrance seems to be the determinant factor of the four thermodynamic equilibria 11 reversible 12 (alpha and beta) and 13 reversible 14 (alpha and beta); aziridinium ions are assumed to be formed as intermediates and one of them has been effectively observed.
Synthese et equilibre thermodynamique des huit 5-O-benzyl-2- (ou 3)- dimethylamino-3 (ou 2)-O-mesyl-α (ou β)-D- (ou ) - furanosides de methyle
摘要:
Regioselectivity of the opening of 2,3-anhydrofuranosides 1 (alpha and beta) and 2 (alpha and beta) by dimethylamine (and by ammonia for 1) has been determined. Thermic stability of the eight corresponding vic-dimethylaminomesylates 11-14 (alpha and beta) in CD3CN and C6D6 has been studied by H-1 NMR : in each case steric hindrance seems to be the determinant factor of the four thermodynamic equilibria 11 reversible 12 (alpha and beta) and 13 reversible 14 (alpha and beta); aziridinium ions are assumed to be formed as intermediates and one of them has been effectively observed.
Regioselectivity of the opening of 2,3-anhydrofuranosides 1 (alpha and beta) and 2 (alpha and beta) by dimethylamine (and by ammonia for 1) has been determined. Thermic stability of the eight corresponding vic-dimethylaminomesylates 11-14 (alpha and beta) in CD3CN and C6D6 has been studied by H-1 NMR : in each case steric hindrance seems to be the determinant factor of the four thermodynamic equilibria 11 reversible 12 (alpha and beta) and 13 reversible 14 (alpha and beta); aziridinium ions are assumed to be formed as intermediates and one of them has been effectively observed.