The solution electron affinities of a series of monosubstituted phenyl-d5 benzenes relative to their perprotiated analogues were measured via electron paramagnetic resonance studies. The equilibrium constant for the electron transfer X-C6H5.- + X-C6D5 half-arrow-right-over-half-arrow-left X-C6H5 + X-C6D5.-, where X = H, C6D5, CN, NO2, OCH3, tert-butyl, was found to be less than unity for all cases. However, this equilibrium constant is closer to unity for those systems where the substituent is electron withdrawing in nature, and it deviates further from unity for those systems that have an electron-donating group as the substituent. A linear free energy relationship was found, and the positive rho value (0.34) is presumably due to the fact that there is a smaller excess charge and spin density from the antibonding electron in the area of the molecule where isotopic substitution takes place, for those systems where the sigma value of the substituent is positive.
One-Pot Palladium(II)-Catalyzed Synthesis of Fluorenones via Decarboxylative Cyclization
摘要:
A one-pot palladium-catalyzed synthesis of fluoronones via decarboxylative cyclization is reported. This protocol offers good yields and tolerates a broad range of functional groups. Based on the extensive experimental data, we propose a plausible decarboxylative insertion mechanism.
Direct Aryl-Aryl Coupling without Pre-Functionalization Enabled by Excessive Oxidation of Two-Electron Ag(I)/Ag(III) Catalyst
作者:Ajay K. Singh、Min-Gyu Kim、Hyune-Jea Lee、Rakhi Singh、Seung Hwan Cho、Dong-Pyo Kim
DOI:10.1002/adsc.201800213
日期:2018.5.16
Reported herein is a catalytic platform for formation of unsymmetrical biaryls by the coupling between inert Csp2−CH3 and Csp2−H via a tandem catalytic strategy. The platform utilizes traditional AgNO3 catalyst and excess amount of K2S2O8 oxidant. The excessive oxidant present converts the traditional one‐electron Ag(I)/Ag(II) chemistry to two‐electron Ag(I)/Ag(III) one, enabling one‐pot synthesis
本文报道的是通过串联催化策略通过惰性C sp 2 -CH 3和C sp 2 -H之间的偶联形成不对称联芳基的催化平台。该平台利用传统的AgNO 3催化剂和过量的K 2 S 2 O 8氧化剂。过量的氧化剂将传统的单电子Ag(I)/ Ag(II)化学转化为两电子Ag(I)/ Ag(III),从而可以通过使用未活化的廉价商品一锅合成芳基-芳基支架化学药品。
The Direct Non-Perturbing Leaching Test in the Phosphine-Free Suzuki-Miyaura Reaction Catalyzed by Palladium Nanoparticles
作者:Alexander N. Kashin、Olga G. Ganina、Andrey V. Cheprakov、Irina P. Beletskaya
DOI:10.1002/cctc.201500329
日期:2015.7.13
normally unreactive in the reaction with phenylboronic acid in the presence of a palladiumnanoparticle catalyst were shown to become involved, if a more reactive aryl iodide is simultaneously participating in the process. The involvement phenomenon can be interpreted as a direct evidence of the formation of smaller and more reactive palladiumnanoparticles through leaching from the initial nanocatalyst
Synthesis of Bi(hetero)aryls via Sequential Oxidation and Decarboxylation of Benzylamines in a Batch/Fully Automated Continuous Flow Process
作者:Bhushan Mahajan、Dnyaneshwar Aand、Ajay K. Singh
DOI:10.1002/ejoc.201800223
日期:2018.6.15
first protocol for synthesis of biaryls and bi(hetero)aryls via sequential oxidation and decarboxylation of benzylamines in a batch/fully automated continuous flow process. Since the batch reaction is less safe, we have chosen a convincing automated flow‐setup to perform it in a controlled and safe manner one‐pot synthesis of biaryls and bi(hetero)aryls.
Discovery and mechanistic investigation of Pt-catalyzed oxidative homocoupling of benzene with PhI(OAc)<sub>2</sub>
作者:S. Masoud Nabavizadeh、Fatemeh Niroomand Hosseini、Chan Park、Guang Wu、Mahdi M. Abu-Omar
DOI:10.1039/c9dt04261j
日期:——
commences by oxidation of the Pt(ii) complex to give the platinum(iv) species [Pt(bhq)(SMe2)(OAc)2](OAc) followed by C-Hactivation of benzene to afford the intermediate [PtPh(bhq)(SMe2)(OAc)](OAc) concurrently with the release of HOAc. A second benzene molecule reacts similarly to give the diphenyl intermediate [PtPh2(bhq)(SMe2)](OAc). C-C bond forming reductive elimination ensues to regenerate Pt(ii) and
Alkyl phenylglyoxylates as radical photoinitiators creating negative photoimages1
作者:Shengkui Hu、Douglas C. Neckers
DOI:10.1039/a701797i
日期:——
Alkyl phenylglyoxylates are shown to be efficient photoinitiators for
acrylate polymerization. Benzoyl and phenyl radicals derived from
intermolecular hydrogen abstraction are the initiating species. A negative
photoimage system was developed based on this observation. The imaging
material consists of a polymeric phenylglyoxylate initiator and
to-be-crosslinked diacrylate monomers. The contrast and sensitivity of
this system have been measured.