Improved procedure for the synthesis of 6-alkoxy-2,3-dihydro-6h-pyran-3-ones (2,3-dideoxy-dl-pent-2-enopyranos-4-uloses). Neat conversion into polyfunctionalized cyclopentenones
✍ Scribed by Bernd Mucha; H. Martin; R. Hoffmann
- Book ID
- 104233167
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- French
- Weight
- 263 KB
- Volume
- 30
- Category
- Article
- ISSN
- 0040-4039
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✦ Synopsis
Abstrae
-The glycosidic bond of 6-alkoxy-2,3-dihydro-6H-pyran-3-ones (3) is made advantageously in the presence of catalytic ZnClz+etherate. A palladium-assisted transformation of 3 affords trans-4-alkoxy-5-hydroxy-2cyclopenten-l-ones (4) in good yield. The construction of the glycosidic linkage is a key reaction in oligosaccharide chemistry.1-3 In the instance of 6-alkoxy-2,3-dihydro_6H_pyran-3-ones (3), the classical Rbnigs-Knorr reaction is not applicable, because a glycosyl halide of 1 cannot easily be obtained.4 Instead, activation of 1 via the crystalline benzoate 2 is feasible. Treatment of 2 with a variety