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。
hydroboration with catecholborane), alkyl iodides (via iodineatom transfer) and xanthates is reported. The reaction proceeds under neutral conditions since no acid is needed to activate the heterocycle and no external oxidant is required. A rateconstant for the addition of a primary radical to N-methoxylepidinium >107 M−1 s−1 was experimentally determined. This rateconstant is more than one order of magnitude
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。
Chain-Amplified Photochemical Fragmentation of <i>N</i>-Alkoxypyridinium Salts: Proposed Reaction of Alkoxyl Radicals with Pyridine Bases To Give Pyridinyl Radicals
作者:Deepak Shukla、Shashishekar P. Adiga、Wendy G. Ahearn、Joseph P. Dinnocenzo、Samir Farid
DOI:10.1021/jo301975j
日期:2013.3.1
N-alkoxypyridiniums, which leads to N–O bond cleavage and alkoxylradical formation, is highly chain amplified in the presence of a pyridine base such as lutidine. Density functional theory calculations support a mechanism in which the alkoxylradicals react with lutidine via proton-coupled electron transfer (PCET) to produce lutidinyl radicals (BH•). A strong electron donor, BH• is proposed to reduce