β-elimination of protected aldono-1,4-lactones as a general approach to the synthesis of 2-keto-3-deoxyaldonic acids containing four to six carbon atoms
✍ Scribed by Gerrit Limberg; Joachim Thiem
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 527 KB
- Volume
- 275
- Category
- Article
- ISSN
- 0008-6215
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✦ Synopsis
The well-known /3-elimination of protected aldonolactones is used for the synthesis of the short-chain 2-keto-3-deoxyaldonic acids 1-4 containing four to six carbon atoms. The key step is the facile /3-elimination step which generates the desired 2-keto-3-deoxy acids as protected enoi 1,4-1actones in excellent yields. Smooth deprotection then leads to the 2-keto-3-deoxyaldonic acids. In the case of the protected o-galactono-l,4-1actone 6 an epimerisation is observed during the elimination process. This enables the synthesis of both 2-keto-3-deoxy-o-hexonic acids with either o-erythro (1) or o-threo (2) configuration in good to excellent yields in only three steps starting with commercially available o-galactono-l,4-1actone (5).