Highly specific fragmentation processes of isomeric mixed esters of phenylsuccinic acid under electron impact
摘要:
AbstractIsomeric mixed dialkyl phenylsuccinates, PhCH(COOR)CH2COOR′, undergo a highly specific elimination of ROH under electron impact. A deuterium‐labelling study showed that the hydrogen atom from the benzylic position 2 is abstracted in this process. These results suggest the occurrence of a ‘hidden’ hydrogen migration of the benzylic hydrogen atom to the carbonylic oxygen of the remote ester group, followed by the elimination of ROH from the adjacent ester group with the involvement of that hydrogen. Alkoxyl group migrations resulting in the formation of [PhCHOR]+ and [PhCHOR′]+ ions are less specific, although the migration of the remote R′O˙ is significantly preferred in all the pairs of isomers examined. Mechanisms are suggested for the formation of the two ions.
Photocatalytic Hydromethylation and Hydroalkylation of Olefins Enabled by Titanium Dioxide Mediated Decarboxylation
作者:Qilei Zhu、Daniel G. Nocera
DOI:10.1021/jacs.0c08688
日期:2020.10.21
photooxidative redox capacity of the valence band of anatase titanium dioxide (TiO2). Mechanisticstudies support a radical-based mechanism involving the photoexcitation of TiO2 with 390-nm light in the presence of acetic acid and other carboxylic acids to generate methyl and alkyl radicals, respectively, without the need for stoichiometric base. This protocol is accepting of a broad scope of alkene
An umpolung approach toward N-aryl nitrone construction: a phosphine-mediated addition of 1,2-dicarbonyls to nitroso electrophiles
作者:Aditi P. Chavannavar、Allen G. Oliver、Brandon L. Ashfeld
DOI:10.1039/c4cc05044d
日期:——
An umpolung strategy toward the chemoselective construction ofN-aryl nitrones employing a phosphine-mediated addition of 1,2-dicarbonyls to nitroso arenes is described.
一种通过膦介导的1,2-二羰基物质加到亚硝基芳烃的化学选择性构建N-芳基亚硝酮的反相策略被描述。
Rhodium(II)-Catalyzed Cross-Coupling of Diazo Compounds
作者:Jørn H. Hansen、Brendan T. Parr、Philip Pelphrey、Quihui Jin、Jochen Autschbach、Huw M. L. Davies
DOI:10.1002/anie.201004923
日期:2011.3.7
left to chance: A convenient protocol for selective cross‐coupling of diazocompounds for the convergent synthesis of alkenes was developed (see scheme; EDG=aryl, heteroaryl, vinyl; R=O‐alkyl, aryl). The selectivity control elements were identified by ReactIR and DFT calculations and provide a framework for the design of viable diazo coupling reactions.
没事了:开发了用于重氮合成烯烃的重氮化合物选择性交叉偶联的便捷方案(见方案; EDG =芳基,杂芳基,乙烯基; R = O-烷基,芳基)。通过ReactIR和DFT计算确定了选择性控制元素,并为可行的重氮偶合反应设计提供了框架。
Blue light-promoted cross-coupling of aryldiazoacetates and diazocarbonyl compounds
作者:Tiebo Xiao、Mingjing Mei、Yuwei He、Lei Zhou
DOI:10.1039/c8cc04609c
日期:——
distinct diazo compounds was described. The reaction produces E-configured trisubstituted alkenes in good yields in the absence of catalysts and additives. The reactive free carbeneintermediates were generated via selective photolysis of one of the two diazo compounds upon blue light irradiation.
All‐Carbon Tetrasubstituted Olefins Synthesis from Diazo Compounds and Iodonium Ylides under Blue LED Irradiation
作者:Yan‐Rui Zhao、Lei Li、Guo‐Yong Xu、Jun Xuan
DOI:10.1002/adsc.202101144
日期:2022.2
tetra-substituted olefins through visible-light promoted coupling of diazo compounds with iodonium ylides was developed. A wide range of all-carbon tetra-substituted olefins was obtained in moderate to good yields. The synthetic values of the current method were further approved by the synthesis of natural isolates modified alkenes and the successful transformation of final olefins into important heterocycles