In a comparative study, reactions between 5-(p-methoxyphenyl)-substituted 3-alkoxy-4-methylthiazole-2(3H)-thiones and appropriate mediators (BrCCl3, Bu3SnH) provided higher yields of alkoxyl radical products (δ-bromohydrins, cyclic ethers, carbonyl compounds) than respective transformations of 5-phenyl- and 5-methyl-substituted derivatives. The unusual selectivity of applied thiohydroxamates to furnish
Spin trapping of alkoxyl radicals generated from 5-methyl and 5-aryl-3-alkoxy-4-methylthiazole-2(3H)-thiones in photochemically induced and microwave-initiated reactions
Methoxyl and isopropoxyl radicals were generated from N-alkoxy-4,5-dimethylthiazole-2(3H)-thiones (λmax∼320 nm) and 5-aryl derivatives (aryl=p-XC6H4; X=MeO, H, AcNH, Cl) (λmax∼335 nm) in photochemically and microwave-induced reactions. Alkoxylradicals were trapped with dimethylpyrrolidine N-oxide and characterized as spin adducts via EPR. Cumyloxyl radicals were liberated in a similar manner from
甲氧基和异丙氧基的基团从生成的ñ -烷氧基-4,5-二甲基噻唑-2(3 H ^)-thiones(λ最大~320纳米)和5-芳基衍生物(芳= p -XC 6 ħ 4 ; X =的MeO, H,AcNH,Cl)的(λ最大~335纳米)在光化学和微波诱导的反应。烷氧基被二甲基吡咯烷N-氧化物捕获并通过EPR表征为自旋加合物。枯基氧基以类似的方式从N-枯基氧基-5-(4-甲氧基苯基)-4-甲基噻唑-2(3 H)-硫酮中释放出来。N的最低能量跃迁发现了值得注意的红移- (羟基)茚并[2,1- d ]噻唑-2(3 H ^) -硫酮(λ最大= 376纳米),如果相比的UV-vis吸收ñ -羟基-4-甲基-5- phenylthiazole- 2(3 ħ) -硫酮(λ最大= 338纳米)。全面描述了烷氧基自由基前体的合成和进行N,O均解的程序。
4- and 4,5-SubstitutedN-Methoxythiazole-2(3H)-thiones - Preparation,UV/Vis Spectra, and Assignment of Electronic Transitions in Comparison toN-Methoxypyridine-2(1H)-thione Using Time-Dependent Density Functional Theory Calculations
absorptions in UV/Visspectra of N-methoxy-4-methylthiazole-2(3H)-thione, N-methoxy-5-(p-methoxyphenyl)-4-methylthiazole-2(3H)-thione, N-methoxypyridine-2(1H)-thione, and selected N-hydroxy derivatives thereof have been assigned to ππ*-type transitions as dominating character, using the results from ab initio calculations [time-dependentdensityfunctionaltheory (TD)RI-BLYP/TZVPP]. Theory further predicts
实验观察到 N-甲氧基-4-甲基噻唑-2(3H)-硫酮、N-甲氧基-5-(对甲氧基苯基)-4-甲基噻唑-2(3H)-硫酮、N-甲氧基吡啶的紫外/可见光谱吸收-2(1H)-硫酮及其选定的 N-羟基衍生物已被指定为 ππ* 型跃迁作为主要特征,使用 ab initio 计算的结果 [时间相关密度泛函理论 (TD)RI-BLYP/TZVPP ]。理论进一步预测,一侧的 N-甲氧基噻唑-2(3H)-硫酮和另一侧的 N-甲基-氧吡啶-2(1H)-硫酮中的电子激发在贡献跃迁的特征和统计权重方面存在显着差异。这些效应主要源于环内硫原子对噻唑-2(3H)-硫酮中轨道能量和形状的贡献,并且可能会被取代基(例如位于 5 位的对甲氧基苯基)增强。 由于计算得出的噻唑硫酮和吡啶硫酮之间的大部分光谱差异是指低强度激发,因此本研究的发现与两个重要的实验事实相关: (i) 除了 UV/Vis 吸收的精确光谱位置的微小变化外,N-羟基-或