Convenient Synthesis of Chiral Pyranones from Carbohydrates
1988; Thieme Medical Publishers (Germany); Volume: 1988; Issue: 11 Linguagem: Inglês
10.1055/s-1988-27741
ISSN1437-210X
AutoresGriselda M. De Fina, Oscar Varela, Rosa M. de Lederkremer,
Tópico(s)Synthesis of Organic Compounds
Resumo2-Acyloxyglycals (2-O-acyl-1,5-anhydrohex-1-enitols) having a D-arabino configuration (1a, b) react highly stereoselectively with alcohols in the presence of a stoichiometric amount of tin(IV) chloride at 0-5°C to (2S, 6S)-6-acyloxymethyl-2-alkoxy-2H-pyran-3 (6H)-ones 2 together with furaldehyde by-products 3. In the case of 2-acyloxyglycals having a D-lyxo (1c, d) or an L-lyxo (4) configuration, reaction occurs readily at - 20°C to form the desired pyranones 2 or 5 without the formation of furaldehydes. All reactions showed high stereoselectivity for α-anomers in the formation of the acetal linkage, except the reaction of the tri-O-benzoyl derivative 1d with methanol. The method reported allows the synthesis of chiral pyranones in higher yield and by a shorter route than the previously reported methods.
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