Permanganate Oxidation Revisited: Synthesis of 3-Deoxy-2-uloses via Indium-Mediated Chain Elongation of Carbohydrates

• Published in: European Journal of Organic Chemistry Vol. 2010; no. 25; pp. 4886 - 4892
• Main Authors: Schmölzer, Christoph, Fischer, Michael, Schmid, Walther
• Format: Book Review Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01-09-2010; WILEY‐VCH Verlag; Wiley-VCH
• Subjects: Allylation; Carbohydrates; Carbohydrates with 4, 5, 6, ... C atoms, dissacharides and oligosaccharides; Carbohydrates. Nucleosides and nucleotides; Chemistry; Exact sciences and technology; Indium; Organic chemistry; Oxidation; Preparations and properties; Thioketals; Carbohydrates; Chemical bond; Deprotection; Chain elongation; Microwave; Oside; Chiral compound; Stereochemistry; Aldehyde; Indium; Allylation; Alkene; Olefin; Deacetylation; Thioketals; Green chemistry; Oxidation; Chemical synthesis; Acid medium; Ethylenic compound
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.201000623

Application of the Barbier‐type indium‐mediated allylation method to suitable substrates offers access to carbohydrates bearing a terminal olefin moiety. The C–C bond forming reaction generates a defined stereochemistry of the new chiral center and tolerates a wide variety of starting aldehydes thus allowing modifications in the carbohydrate backbone. Further transformations of the alkene moiety via an environmentally benign and subtle controlled protocol using potassium permanganate gives rise to the structural motif of 3‐deoxy‐2‐uloses in good yields. The final part of the reaction sequence focuses on the deprotection of the acetyl groups essential for the success of the oxidation step. The acidic and labile 3‐deoxy position of the target molecule is prone to elimination applying standard deacetylation conditions and therefore demands derivatisation of the molecule. The introduction of a thioketal moiety using microwave conditions shows promising results and subsequent standard transformations are applicable leading to the desired products.
The oxidation of terminal olefins derived from chain‐elongated carbohydrates with potassium permanganate offers direct access to the structural motif of the 3‐deoxy‐2‐uloses in good yields and selectivities.