Diastereoselective aza-Michael addition for synthesis of carbohydrate-derived spiropiperazinones
摘要:
3-Deoxy-3-C-nitromethylene-1,2:5,6-di-O-isopropylidene--d-glucofuranose reacts with amino acid esters according to the aza-Michael addition pathway. The obtained adducts after reduction of the nitro group spontaneously lactamize and provide novel carbohydrate-derived spiropiperazinones.[GRAPHICS].
Abstract Michaeladdition reactions of O-nucleophiles to C(3) exocyclic nitromethylene derivative of diacetone glucose are reported. The reactions with primary alcohols proceed at ambient temperature in the presence of different bases with good yields and give products with excellent diastereoselectivity. The addition of the nucleophile occurs from the β-face of the carbohydrate as shown by single
摘要 报道了 O-亲核试剂与双丙酮葡萄糖的 C(3) 环外硝基亚甲基衍生物的迈克尔加成反应。与伯醇的反应在环境温度下在不同碱的存在下以良好的收率进行,并得到具有优异非对映选择性的产物。如单晶 X 射线分析所示,亲核试剂的添加发生在碳水化合物的 β 面。与仲醇反应的产物产率低,而酚类化合物不反应。在某些条件下,观察到起始材料的异构化。
Synthesis and X-ray studies of novel 3-C-nitromethyl-hexofuranoses
A practical method for the synthesis of three novel 3-C-nitromethyl-hexofuranoses is reported. The Henry reaction on a 1,2: 5,6-di-O-isopropylidene-alpha-D-gulofuranose-derived ketone provided a 3-C-branched gulo-isomer as the sole reaction product. The dehydration-rehydration of the latter yielded an isopropylidene-protected 3-C-nitromethyl-galactofuranose. The reaction sequence can be also used for the synthesis of a 3-deoxy-3-C-nitromethyl-hexofuranose derivative with a gulo-configuration. Two of the newly obtained carbohydrate derivatives were characterized by X-ray crystallography. (C) 2014 Elsevier Ltd. All rights reserved.