of sucrose fatty acid esters to undergo intramolecular migrations in organic medium and the regioselectivity of some transesterifications of sucrose were investigated by HPLC, in situ NMR spectroscopy and preparative methods. Extensive acylation on secondary positions of the glucose moiety followed by migrations is general for base catalysed transesterification. The stability of 3‐ and 6‐O‐acyl derivatives
unprotected sucrose in N,N-dimethylformamide and the appropriate 3-acylthiazolidine-2-thiones 6 or 3-acyl-5-methyl-1,3,4-thiadiazole-2(3H)-thiones 7. A selective ionization of the free sugar by sodium hydride or triethylamine, followed by acylation with 6, gave 2-O-acylsucroses which were subjected in situ to intramolecular isomerizations using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or an aqueous solution
Sugar chemistry without protecting groups: a novel regioselective synthesis of 6-O-acyl-D-glucopyranoses and methyl-6-O-acyl-α--glucopyranosides
作者:Daniel Plusquellec、Krystyna Baczko
DOI:10.1016/s0040-4039(00)96390-1
日期:1987.1
hydroxyl groups of α--glucose and methyl-α--glucoside were selectively esterified by treating the free sugars with -acylthiazolidine-2-thiones, thus affording respectively 6--acyl--glucopyranoses and methyl-6--acyl-α--glucopyranosides in high yields. This new reaction is compared with our previous synthesis of 1--acyl-β--glucopyranoses from β--glucose and interpreted in terms of anomeric effect.