The reductive singleelectrontransfer (SET) umpolung amination of aldehyde-derived hydrazones has been developed through visible-light-promoted photoredox catalysis. The ideal transformation of hydrazones into the corresponding hydrazonamide through selective carbon–hydrogen (C–H) bond functionalization represents one of the most step- and atom-economical methods. This SET umpolung strategy features
products, and one‐pot syntheses. Mechanistic analyses and theoretical calculations indicate that this reaction is enabled by a novel aminylradical/polar crossover mechanism, with the aminylradical being oxidized into the corresponding aminyl cation through a single electrontransfer (SET) process.
Dye-Sensitized Photooxygenation of the CN Bond. 5. Substituent Effects on the Cleavage of the CN Bond of <i>C</i>-Aryl-<i>N</i>-aryl-<i>N</i>-methylhydrazones<sup>1</sup>
作者:Ihsan Erden、Pinar Ergonenc Alscher、James R. Keeffe、Colin Mercer
DOI:10.1021/jo050014t
日期:2005.5.1
involved in the mechanism. We postulate a mechanism in which the initial event is exothermic electron transfer from the hydrazone to 1O2 leading to an ion−radical caged pair. Subsequent covalent bondformation between the hydrazone carbon and an oxygen atom is rate controlling. The transition state for this step also has a lower enthalpy than the starting reactants, but the free energy of activation
标题化合物在C干净地切割由单线态氧N键(1 Ò 2,1 Δ克得到芳醛)和ñ -芳基- Ñ -methylnitrosamines。这些反应在-78°C处比在室温下发生的速度更快。使用竞争性方法研究了取代基在C-芳基和N-芳基上的变化的影响。所得率比的良好的相关性与取代基常数(σ -或σ +所获得的)产生很小到非常小的ρ值,表明反应物和决定速率的过渡态之间的电荷分布从很小到很小。C-芳基部分上的吸电子基团通过preferential的优先稳定化而在某种程度上延迟了反应。另一方面,电子给体稍微稳定了决定过渡态的速率。N-芳基上的取代基几乎没有作用。未观察到3,5-二叔丁基苯酚的抑制作用,表明该机制未涉及自由基(未老化的)自由基中间体。我们假设一种机制,其中初始事件是放热电子从hydr到1 O 2的转移导致离子自由基笼对。carbon碳和氧原子之间随后的共价键形成是速率控制的。该步骤的过渡状态也
Electrochemical Oxidative Phosphorylation of Aldehyde Hydrazones
The electrochemical phosphorylation of aldehyde hydrazones has been developed under exogenous oxidant-free conditions. The strategy provides expedient access to highly functionalized α-iminophosphine oxides with ample scope and broad functional group tolerance by means of mild, user-friendly electrolysis, in an undivided cell.
Oxidative C(sp<sup>2</sup>)–H Phosphonation of Aldehyde Hydrazones
作者:Pan Xu、Zhongkai Wu、Nengneng Zhou、Chengjian Zhu
DOI:10.1021/acs.orglett.6b00257
日期:2016.3.4
A K2S2O8/Cu(OAc)2-mediated oxidative C–H/P–H cross-coupling of aldehyde hydrazones with diphenylphosphine oxide for the direct preparation of functionalized α-iminophosphine oxides is reported. The reaction shows good functional group tolerance and proceeds smoothly under mild conditions. This strategic protocol for C–P bond formation is facilitated by a net oxidative aminyl radical–polar crossover
据报道,AK 2 S 2 O 8 / Cu(OAc)2介导的乙与二苯基膦氧化物的氧化C–H / P–H交叉偶联可直接制备官能化的α-亚氨基膦氧化物。该反应显示出良好的官能团耐受性,并且在温和条件下平稳进行。净氧化性胺基自由基-极性交叉过程促进了C-P键形成的这一战略方案。