and cyano) substituted glycals with a range of sugar derived thiols gave the corresponding β-manno type 3-deoxy-3-S-disaccharides with full regio- and stereoselectivity. The configuration of the glycals (arabino vs. lyxo) and the size of the protectinggroups had no significant effect on the outcome of the transformations. Formation of by-products was tracked down by LCMS studies and correlated with
rationale, which might be important for the redox behavior of other allylic systems. Finally, donors and acceptors in the 1-position exert the strongest influence on the oxidation stability, shifting the potentials by almost 1 V and resulting in different follow-up reactions of the cerium(IV)-mediated additions of malonates. It is the remarkable oxidation stability of glycals that makes them valuable
通过它们在溶液中的氧化还原数据、计算的 HOMO 能量以及添加在硝酸铈 (IV) 铵存在下产生的亲电子自由基的行为,糖醛在氧化条件下的显着稳定性变得明显。获得了高达 2.03 V 与二茂铁的氧化电位,这对于环状烯醇醚来说非常高,但与自由基反应的反应时间密切相关。保护基团对氧化稳定性和糖类的 HOMO 能有很大影响,因为 E(ox) 从 O-甲硅烷基经过 O-苄基转移到 O-乙酰基超过 500 mV。有趣的是,这种效应必须通过 sigma 键传递,甚至高达苯甲酸酯基团的对位,正如碳水化合物中远程取代基的广泛变化所证实的那样。提出了相邻 CO 键的 sigma*-轨道与双键的 HOMO 的有利相互作用作为机械原理,这对于其他烯丙基系统的氧化还原行为可能很重要。最后,1 位的供体和受体对氧化稳定性的影响最大,将电位移动了近 1 V,并导致铈 (IV) 介导的丙二酸酯添加的不同后续反应。糖醛显着的
Addition of malonyl radicals to glycals with C-1 acceptor groups: remarkable influence of the substituents on the product distributionElectronic supplementary information (ESI) available: NMR data for C-2 branched sugar derivatives. See http://www.rsc.org/suppdata/cc/b2/b202898k/
The ceric(IV) ammonium nitrate (CAN)-mediated radical addition of dimethyl malonate to glycals 1 affords methyl glycosides 2 and ortho esters 3 as main products; the product distribution strongly depends on the substitution pattern at the 1-position, which can be rationalized in terms of the oxidation potentials of the intermediary anomeric radicals.
substituted d-lyxo configured O-peracetylated glycals, while the transformation of the 1-cyano derivative gave a 2,3-vicinal diazide in low yield. The 1-carbamoyl d-arabino configured O-perbenzoylated glycal gave a mixture of α-d-gluco and α-d-manno configured azidohydroxylated products with d-gluco preference. The analogous 1-methoxycarbonyl derivative gave an inseparable product mixture and no transformation
Strong Binding of <i>C</i>-Glycosylic1,2-Thiodisaccharides to Galectin-3─Enthalpy-Driven Affinity Enhancement by Water-Mediated Hydrogen Bonds
作者:László Lázár、Anastasia S. Tsagkarakou、George Stravodimos、George Kontopidis、Hakon Leffler、Ulf J. Nilsson、László Somsák、Demetres D. Leonidas
DOI:10.1021/acs.jmedchem.3c00882
日期:2023.9.14
polarization and isothermal titration calorimetry to show low micromolar Kd values. The best inhibitor displayed a Kd value of 8.0 μM. An analysis of the thermodynamic binding parameters revealed that the binding Gibbs free energy (ΔG) of the new inhibitors was dominated by enthalpy (ΔH). The bindingmode of the four most efficient 1,2-thiodisaccharides was also studied by X-ray crystallography that
Galectin-3 参与许多疾病的多种途径,包括癌症、纤维化和糖尿病,它是开发新型治疗剂以满足未满足的医疗需求的经过验证的药物靶标。通过O-过酰基化1-C-取代糖醛和1-硫代-吡喃糖的光引发硫醇-烯点击反应合成了具有C-糖基官能团的新型1,2-硫二糖。随后的整体脱保护产生了测试化合物,通过荧光偏振和等温滴定量热法研究了其与人半乳糖凝集素-3 的结合,显示出低微摩尔 K d值。最佳抑制剂的Kd值为8.0 μM。热力学结合参数的分析表明,新抑制剂的结合吉布斯自由能(Δ G )由焓(Δ H)主导。还通过 X 射线晶体学研究了四种最有效的 1,2-硫二糖的结合模式,揭示了水介导的氢键在赋予新抑制剂以焓驱动的亲和力增强方面的独特作用。这种 1,2-硫二糖型支架代表了半乳糖凝集素 3 抑制剂发现的新先导,并为进一步开发提供了多种可能性。