Phenylglyoxylic Acid: An Efficient Initiator for the Photochemical Hydrogen Atom Transfer C−H Functionalization of Heterocycles
作者:Giorgos N. Papadopoulos、Maroula G. Kokotou、Nikoleta Spiliopoulou、Nikolaos F. Nikitas、Errika Voutyritsa、Dimitrios I. Tzaras、Nikolaos Kaplaneris、Christoforos G. Kokotos
DOI:10.1002/cssc.202001892
日期:2020.11.20
C−H functionalization at the α‐position of heterocycles has become a rapidly growing area of research. Herein, a cheap and efficient photochemical method was developed for the C−H functionalization of heterocycles. Phenylglyoxylic acid (PhCOCOOH) could behave as an alternative to metal‐based catalysts and organic dyes and provided a very general and wide array of photochemical C−H alkylation, alkenylation
of alkyl and acyl radicals onto electron-poor olefins or diisopropyl azodicarboxylate has been carried out on a multi-gram scale under continuous flow conditions. The process is based on the use of the inorganic photocatalyst tetrabutylammonium decatungstate (TBADT), which is capable to activate selectively a variety of CH bonds in different substrates, including aldehydes, amides, ethers and alkanes
已经在连续流动条件下以克为单位进行了一组烷基和酰基自由基在贫电子烯烃或偶氮二羧酸二异丙酯上的原子经济自由基共轭加成反应。该方法基于使用无机光催化剂四丁基癸二酸铵(TBADT),它能够选择性地活化不同底物(包括醛,酰胺,醚和烷烃)中的多种CH键。根据该程序已经合成了广泛的合成靶,包括1,4-双官能化的衍生物(例如1,4-二酮或酮酯)。所有反应均在中观条件下进行规模的流量光反应器,包括缠绕在水冷500 W中压汞蒸气灯周围的紫外线透明FEP管(氟化乙烯丙烯)的盘管。这种光化学设备的使用导致了停留时间的减少,相对于相应的批处理过程所测得的停留时间而言,STY(时空产率)和生产率值显着提高,通常会导致整体效率的提高。过程的可持续性(过程质量强度– PMI –值低至10 kg kg -1)。
Transition-Metal-Catalyzed Aldehydic C−H Activation by Azodicarboxylates
作者:Daesung Lee、Ryan D. Otte
DOI:10.1021/jo035456o
日期:2004.5.1
Rhodium acetate-catalyzed hydroacylation between aldehydes and an activated form of NN bond was achieved under mild conditions to provide efficient access to a variety of hydrazino imides. Good selectivity for the aldehydic C−Hactivation relative to the ene-type reaction was observed with aldehydes having unsaturation both at terminal and internal positions.
Photochemical Activation of a Hydroxyquinone-Derived Phenyliodonium Ylide by Visible Light: Synthetic and Mechanistic Investigations
作者:Mona Jalali、Curtis C. Ho、Rebecca O. Fuller、Nigel T. Lucas、Alireza Ariafard、Alex C. Bissember
DOI:10.1021/acs.joc.0c02592
日期:2021.1.15
We have identified and extensively investigated the photochemical activation and reaction of a hydroxyquinone-derived phenyliodonium ylide in the presence of visible light using experiment and theory. These studies revealed that in its photoexcited state this iodonium is capable of facilitating a range of single-electron transfer (SET) processes, including hydrogen atom transfer (HAT), a Povarov-type
Tetrabutylammonium decatungstate (TBADT) accelerated the addition of C-H bonds to the N=N double bond of diisopropyl azodicarboxylate (DIAD) under irradiation conditions. The photoinduced three-component coupling between cyclic alkanes, CO, and DIAD was also achieved to give the corresponding acyl hydrazides.