THIAZOLE-BASED SYNTHESIS OF FORMYL C-GLYCOSIDES

被引:132
作者
DONDONI, A
SCHERRMANN, MC
机构
[1] Dipartimento di Chimica, Laboratorio di Chimica Organica, Università, Ferrara
关键词
D O I
10.1021/jo00100a050
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
A method for the installation of the formyl group at the anomeric position of pyranoses and furanoses starting from the corresponding lactones has been developed. The strategy involves the addition of 2-lithiothiazole to the sugar lactone, followed by the silane reduction of the acetylated resultant ketol and the unmasking of the formyl group from the thiazole ring. All steps have been studied in some details to improve chemical efficiency and stereochemical control. Hence, reversed alpha:beta ratios of ketols were found in kinetic and thermodynamic mixtures, the former being consistent with a steric effect control of the substituents and the latter by the electronic effect of the ring oxygen. Seven sugar aldehydes with different D-pyranosidic (2,3,4,6-tetra-O-benzyl-gluco, -galacto, and -manno, 2-azido-3,4,6-tri-O-benzyl-2-deoxy-galacto) and D-furanosidic moieties (5-O-benzyl-2,3-isopropylidene-ribo; 2,3,5-tri-O-benzyl-ribo; 2,3:5,6-di-O-isopropylidene-manno) were prepared in 52-65% isolated overall yield from the corresponding lactone.
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页码:6404 / 6412
页数:9
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