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.
Selectivity in the SmI2-induced deoxygenation of thiazolylketoses for formyl C-glycoside synthesis and revised structure of C-ribofuranosides
作者:Alessandro Dondoni、Paolo Formaglio、Alberto Marra、Alessandro Massi
DOI:10.1016/s0040-4020(01)00736-0
日期:2001.9
Deoxygenation of thiazolylketose acetates using SmI2–(CH2OH)2 or TMSOTf–Et3SiH affords thiazolyl C-glycosides with opposite α/β ratios. Examination of the thiazolyl α- and β-C-ribofuranoside pair by NOE experiments reveals that the earlier configuration assigned to one of these isomers has to be revised. Having prepared authentic anomeric α- and β-ribofuranose aldehydes from the corresponding thiazolyl
Synthesis of pyridazine and thiazole analogs as SGLT2 inhibitors
作者:Suk Youn Kang、Kwang-Seop Song、Junwon Lee、Sung-Han Lee、Jinhwa Lee
DOI:10.1016/j.bmc.2010.06.076
日期:2010.8
With anticipation of the improvement in biological aspects in our SGLT2 program, novel pyridazinyl and thiazolyl analogs were designed and efficiently synthesized. The installation of the pyridazine ring at the anomeric carbon of D-glucopyranose was carried out in a stereoselective fashion. On the other hand, a series of thiazolyl analogs was also synthesized through a coupling reaction between perbenzyl gluconolactone 9 and 2-lithiothiazole. Biological activities of the compounds thus prepared were evaluated by the in vitro SGLT2 inhibition assay. Considering assay results, the novel benzylpyridazinyl and benzyl-thiazolyl analogs, disclosed in this article, could be a quick reference to prospective SGLT2 inhibitors useful for pharmacotherapy. (C) 2010 Elsevier Ltd. All rights reserved.
Thiazole-based synthesis of C-glycosyl aldehydes
作者:Alessandro Dondoni、Marie-Christine Scherrmann
DOI:10.1016/s0040-4039(00)79319-1
日期:1993.11
The formylation at the anomeric carbon of the model sugars 2,3,4,6-tetra-O-benzyl-D-glucopyranose and 2,3:5,6-di-O-isopropylidene-D-mannofuranose is carried out by addition of 2-lithiothiazole to the corresponding lactones followed by reductive dehydroxylation and thiazole to formyl deblocking.