已经开发了通过有氧氧化裂解产生芳基甲二酸或串联好氧氧化/苯甲酸重排/脱羧以产生二芳基甲酮的二芳基酮的化学选择性转化。该转化是可控的,并且适用于广泛范围的底物,并以良好至优异的产率提供所需的产物。具有控制反应的机械洞察力,11 H NMR追踪和单晶X射线衍射揭示了一个复杂的机理网络,其中提出并验证了两个常见的中间体,α-酮氢过氧化物和二芳基乙二酮,以及三个可能的途径。这些途径是相互联系的,可以通过改变反应条件来合理地切换。这种方法能够实现可扩展的合成并获得许多有价值的化合物,包括维生素B 3,苯二酸和非甾体抗炎药酮洛芬。本协议代表了在利用复杂的机械网络来控制反应路径,从同一类起始原料获得不同合成方法方面迈出的一步。
Transition-Metal-Free and Chemoselective NaO<sup><i>t</i></sup>Bu–O<sub>2</sub>-Mediated Oxidative Cleavage Reactions of <i>vic</i>-1,2-Diols to Carboxylic Acids and Mechanistic Insight into the Reaction Pathways
作者:Sun Min Kim、Dong Wan Kim、Jung Woon Yang
DOI:10.1021/ol501012f
日期:2014.6.6
method for efficient oxidativecleavage of vic-1,2-diols using a NaOtBu–O2 system resulted in the formation of carboxylic acids in high yields. The present protocol is an eco-friendly alternative to a conventional transition-metal-based method. This new strategy allows large-scale production with nonchromatographic purification while also suppressing competitive reactionpathway such as benzilic acid
一种使用NaO t Bu–O 2系统对vic -1,2-二醇进行有效氧化裂解的方法,可高产率地形成羧酸。本协议是传统的基于过渡金属的方法的环保替代。这种新策略可以通过非色谱纯化进行大规模生产,同时还可以抑制竞争性反应途径,例如苯甲酸重排。
Heterogeneous carbon nitride photocatalyst for C–C bond oxidative cleavage of vicinal diols in aerobic micellar medium
作者:Tengfei Niu、Shengjun Chen、Mei Hong、Tianhao Zhang、Jiayang Chen、Xinyu Dong、Bangqing Ni
DOI:10.1039/d0gc01727b
日期:——
A green and efficient visible-light promoted aerobic oxidative C–C bond cleavage of vicinal diols in micellarmedium has been developed. This protocol used graphitic carbon nitride with nitrogen vacancies (CN620) as a metal-free recyclable photocatalyst and CTAB as surfactant in water. Control experiments and the ESR results indicated that superoxide radicals and valence band holes played an important
105 for the reduction to alcohol and pinacol formation, respectively, and are very stable so that they can be recycled for at least 10 times in the reactions without significant loss of catalytic activity. The additional advantages of this method include good functional group tolerance, mild reaction conditions, the allowance of selectively reducing aldehydes in the presence of ketones, and easiness
quantitative reduction of aromatic aldehydes, ketones, diketones and oxo aldehydes to alcohols by use of TiCl3/NH3 in aqueous methanol solution is reported. The reducing system distinguishes between different classes of aldehydes and/or ketones, and many functionalities that usually do not survive under reducing conditions are tolerated well. The concept of reversal of chemoselectivity has also been developed
Magnesium-Mediated Carbon−Carbon Bond Formation in Aqueous Media: Barbier−Grignard Allylation and Pinacol Coupling of Aldehydes
作者:Wen-Chun Zhang、Chao-Jun Li
DOI:10.1021/jo982497p
日期:1999.4.1
alkylation of aldehydes with alkyl halides was studied in aqueousmedia. The reaction of aromatic aldehydes with allyl halides is highly effective with either THF or water as the reaction solvent but poor in a mixture of THF/water. It was found that the magnesium-mediated allylation of aldehydes with allyl bromide and iodide proceeds effectively in aqueous 0.1 N HCl or 0.1 N NH(4)Cl. Aromatic aldehydes reacted
在含水介质中研究了镁介导的Barbier-Grignard型醛与烷基卤化物的烷基化反应。用THF或水作为反应溶剂,芳族醛与烯丙基卤的反应非常有效,但是在THF /水的混合物中效果较差。已经发现,镁与烯丙基溴和碘的醛介导的烯丙基化在0.1 N HCl或0.1 N NH(4)Cl水溶液中有效进行。芳族醛在脂肪族醛的存在下发生化学选择性反应。当脂族和芳族醛官能团同时存在于同一分子中时,也观察到排他选择性。在不存在烯丙基卤的情况下,醛和酮与镁在0.1 N NH(4)Cl水溶液中反应形成高产率的相应频哪醇偶联产物。频哪醇反应的有效性受到羰基周围空间环境的强烈影响。脂肪醛和简单的烷基卤化物在用于烷基化或频哪醇偶联反应的反应条件下呈惰性。