Department of Chemistry, Faculty of Technology, Tomas Bata University in Zlin, Zlin, Czech Republic.
Carbohydr Res. 2010 Apr 19;345(6):768-79. doi: 10.1016/j.carres.2010.01.023. Epub 2010 Feb 4.
A comparative study for selective glucosylation of N-unsubstituted 4-hydroxyquinolin-2(1H)-ones into 4-(tetra-O-acetyl-beta-D-glucopyranosyloxy)quinolin-2(1H)-ones is reported. Four glycosyl donors including tetra-O-acetyl-alpha-D-glucopyranosyl bromide, beta-D-glucose pentaacetate, glucose tetraacetate and tetra-O-acetyl-alpha-D-glucopyranosyl trichloroacetimidate were tested, along with different promoters and reaction conditions. The best results were obtained with tetra-O-acetyl-alpha-D-glucopyranosyl bromide with Cs(2)CO(3) in CH(3)CN. In some cases the 4-O-glucosylation of the quinolinone ring was accompanied by 2-O-glucosylation yielding the corresponding 2,4-bis(tetra-O-acetyl-beta-D-glucopyranosyloxy)quinoline. Next, 4-(tetra-O-acetyl-beta-D-glucopyranosyloxy)quinolin-2(1H)-ones were deacetylated into 4-(beta-D-glucopyranosyloxy)quinolin-2(1H)-ones with Et(3)N in MeOH. In some instances the deacetylation was accompanied by the sugar-aglycone bond cleavage. Structure elucidation, complete assignment of proton and carbon resonances as well as assignment of anomeric configuration for all the products under investigation were performed by 1D and 2D NMR spectroscopy.
本文报道了 N-未取代的 4-羟基喹啉-2(1H)-酮的选择性葡糖基化反应的比较研究。测试了四种糖基供体，包括四-O-乙酰基-α-D-吡喃葡萄糖基溴、β-D-葡萄糖五乙酸酯、葡萄糖四乙酸酯和四-O-乙酰基-α-D-吡喃葡萄糖基三氯乙酰亚胺，以及不同的促进剂和反应条件。使用 Cs(2)CO(3)在 CH(3)CN 中的四-O-乙酰基-α-D-吡喃葡萄糖基溴得到了最佳结果。在某些情况下，喹啉酮环的 4-O-葡糖基化伴随着 2-O-葡糖基化，生成相应的 2,4-双（四-O-乙酰基-β-D-吡喃葡萄糖基）喹啉。接下来，用 Et(3)N 在 MeOH 中将 4-(四-O-乙酰基-β-D-吡喃葡萄糖基)喹啉-2(1H)-酮脱乙酰基为 4-(β-D-吡喃葡萄糖基)喹啉-2(1H)-酮。在某些情况下，脱乙酰基伴随着糖-糖苷键的断裂。通过 1D 和 2D NMR 光谱对所有研究产物进行了结构阐明、质子和碳共振的完全归属以及端基构型的归属。
