报道了N-甲氧基吡啶鎓盐与由烯烃(通过与儿茶酚硼烷的硼氢化反应)、烷基碘化物(通过碘原子转移)和黄原酸盐产生的烷基自由基的单烷基化反应。反应在中性条件下进行,因为不需要酸来活化杂环,也不需要外部氧化剂。将伯自由基添加到N-甲氧基吡啶鎓的速率常数>10 7 M -1 s -1是通过实验确定的。该速率常数比将伯烷基自由基添加到质子化来比啶所测得的速率常数大一个数量级以上,这表明甲氧基吡啶鎓盐对自由基具有显着的反应性。该反应已用于制备独特的吡啶化萜类化合物,并扩展到富电子烯烃(包括烯醇酯、烯醇醚和烯酰胺)的三组分碳吡啶基化反应。
Diacetyl as a “traceless” visible light photosensitizer in metal-free cross-dehydrogenative coupling reactions
作者:Chia-Yu Huang、Jianbin Li、Wenbo Liu、Chao-Jun Li
DOI:10.1039/c8sc05631e
日期:——
light-sensitive and “traceless” hydrogen atom abstractor to achieve metal-free cross-dehydrogenative Minisci alkylation under mild conditions. Mechanistic studies supported hydrogen atom transfer (HAT) between an activated C(sp3)–H substrate and diacetyl. Moreover, with the assistance of di-tert-butyl peroxide (DTBP), the scope of the reaction could be extended to strong aliphatic C–H bonds via diacetyl-mediated
The reactions of dioxanyl and cyclohexylradicals with 2- and 3-X-pyridines (X = CN, COMe, CO2Me) give a single substitution product deriving by addition at the 5- and 6-positions respectively; with 4-X-pyridines substitution occurs preferentially at the 3-position. If the reactions are carried out with protonated pyridines other positional isomers are obtained. From the synthetic point of view the
Photocatalytic Aerobic Coupling of Azaarenes and Alkanes via Nontraditional Cl<sup>•</sup> Generation
作者:Manotosh Bhakat、Bitasik Khatua、Joyram Guin
DOI:10.1021/acs.orglett.2c01784
日期:2022.7.29
photocatalytic generation of Cl• from a common chlorinated solvent, dichloroethane, under aerobic conditions and its successful utilization toward the cross-dehydrogenative coupling of alkanes and azaarenes via hydrogen atom transfer with Cl•. The process is free from chloride salt, toxic oxidant, and UV light. It is applicable to a broad spectrum of substrates. The proposed mechanism involving Cl• is