Synthese et equilibre thermodynamique des huit 5-O-benzyl-2- (ou 3)- dimethylamino-3 (ou 2)-O-mesyl-α (ou β)-D-xylo (ou arabino) - furanosides de methyle
✍ Scribed by Marie-Béatrice Giudicelli; Marie-Agnès Thomé; Dominique Picq; Daniel Anker
- Publisher
- Elsevier Science
- Year
- 1992
- Tongue
- French
- Weight
- 971 KB
- Volume
- 48
- Category
- Article
- ISSN
- 0040-4020
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✦ Synopsis
Regioselectivity of the opening of 2,3-anhydrofuranosides 1 (a and 8) and 2 (a and /3) by dimethylamine (and by ammonia for 1) has been determined. Thermic stability of the eight corresponding vie-dimethylaminomesylates 11-14 (a and /3) in CD CN died by 'H NMR : in each case steric hindrance seems to be the d and C,D, has been stueterminant factor of the four thermodynamic equilibria 11~~ 12 (a and 8) and 13 ~14 (a and 8) ; aziridinium ions are assumed to be formed as intermediates and one of them has been effectively observed. RCsumk : La rkgiosklectivitk de I'ouverture des 2,3-anhydrofuranosides 1 (a et /3) et 2 (a et 8) par la dimethylamine (et par I'ammoniaque dans ie cas de 1) a Bti determinde. La stabiliti thermique des huit ric-dimethylaminomesylates correspondants 11-14 (a et /3) dans CDaCN et C,D, a Bte 6tudiee a I'aide de ia RMN 'H. La position des quatre Bquilibres thermodynamtques obser-v&, Il== 12 (a et 8) et 131 14 (a et 8) depend principalement de I'encombrement stkique ; des ions aziridinium semblent btre les intermkdiaires de ces equilibres et I'un d'entre eux a pu &tre mis en hvidence.