One-pot alpha-glycosylation pathway via the generation in situ of alpha-glycopyranosyl imidates in N,N-dimethylformamide
| Autor: | Akira Miyachi, Yoshiko Miura, Yuko Shingu, Yoshihiro Nishida, Kazukiyo Kobayashi |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Anomer
Glycosylation Magnetic Resonance Spectroscopy Chemistry Organic Chemistry Cationic polymerization Carbohydrates Halide Dimethylformamide General Medicine Carbon-13 NMR Biochemistry Medicinal chemistry Acceptor Analytical Chemistry carbohydrates (lipids) chemistry.chemical_compound Bromide Reagent Imidoesters Organic chemistry lipids (amino acids peptides and proteins) Solvent effects Pyrans |
| Zdroj: | Carbohydrate research. 340(14) |
| ISSN: | 0008-6215 |
| Popis: | Divergent pathways are disclosed in the activation of 2- O -benzyl-1-hydroxy sugars by a reagent combination of CBr 4 and Ph 3 P, all of which afford one-pot α-glycosylation methods. When this reagent is used in CH 2 Cl 2 , the 1-hydroxy sugar is converted to the α-glycosyl bromide in a conventional way and leads to the one-pot α-glycosylation method based on a halide ion-catalytic mechanism. In either DMF or a mixture of DMF and CHCl 3 , however, alternative α-glycosyl species are generated. From the 1 H and 13 C NMR study of the products, as well as the reactions using Vilsmeier reagents [(CH 3 ) 2 N + CHX]X − (X = Br and Cl), these were identified as cationic α-glycopyranosyl imidates having either Br − or Cl − counter ion. The cationic α-glycosyl imidate (Br − ), derived specifically in the presence of DMF, is more reactive than the α-glycosyl bromide and thus is responsible for the accelerated one-pot α-glycosylation. The one-pot α-glycosylation methodology performed in DMF was assessed also with different types of acceptor substrates including tertiary alcohols and an anomeric mixture of 1-OH sugars. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect