1579-72-2Relevant articles and documents
Effect of ortho substituents on carbonyl carbon 13C NMR chemical shifts in substituted phenyl benzoates
Nummert, Vilve,Piirsalu, Mare,Maeemets, Vahur,Vahur, Signe,Koppel, Ilmar A.
, p. 1155 - 1165 (2009)
13C NMR spectra of 37 ortho-, meta-, and para-substituted phenyl benzoates, containing substituents in benzoyl and phenyl moiety, 4 ortho-substituted methyl and 5 ethyl benzoates as well as 9 R-substituted alkyl benzoates have been recorded. The influence of the ortho substituents on the carbonyl carbon 13C NMR chemical shift, δCO, was found to be described by a linear multiple regression equation containing the inductive, σI, resonance, σRo, and steric, EsB, or ν substituent constants. For all the ortho-substituted esters containing substituents in the acyl part as well as the phenyl part, the substituent-induced reverse inductive effect (ρIR > 0), and the negative steric effect (δorthosB were observed. In the case of ortho substituents in the phenyl part, the resonance effect was negligible. Due to inductive effect, the ortho electron-withdrawing substituents showed an upfield shift or shielding of the carbonyl carbon, while the electron-donating substituents had an opposite effect. Because of the sterical consequences, ortho substituents revealed a deshielding effect on the 13C NMR chemical shift of the carbonyl carbon. For all the meta- and para-substituted esters, the reverse substituent-induced inductive and resonance effects (ρIR4NBr and 2.25M Bu4NBr, and the IR frequencies, νCO, for the ortho-, meta-, and para-substituted phenyl benzoates and alkyl benzoates were correlated nicely with the corresponding 13C NMR substituent chemical shifts, ΔδCO. Copyright
Palladium-Catalyzed Para-Selective Difluoromethylation of Arene Esters
Tu, Guangliang,Wang, Dongjie,Yuan, Chunchen,Zhang, Jingyu,Zhao, Yingsheng
, p. 10740 - 10749 (2020/09/18)
Highly efficient, palladium-catalyzed, para-selective difluoromethylation of arene esters has been developed using [1,1′-biphenyl]-2-dicyclohexylphosphine as the effective ligand. A wide variety of arene esters bearing various functional groups were all compatible with the reaction conditions, leading to para-difluoromethylated products in moderate to good yields. Moreover, benzoylamide and benzenesulfonamide were also well-tolerated, suggesting that this novel catalyst system has broad applications to a variety of substrates.
Transesterification of (hetero)aryl esters with phenols by an Earth-abundant metal catalyst
Chen, Jianxia,Namila,Bai, Chaolumen,Baiyin, Menghe,Agula, Bao,Bao, Yong-Sheng
, p. 25168 - 25176 (2018/07/29)
Readily available and inexpensive Earth-abundant alkali metal species are used as efficient catalysts for the transesterification of aryl or heteroaryl esters with phenols which is a challenging and underdeveloped transformation. The simple conditions and the use of heterogeneous alkali metal catalyst make this protocol very environmentally friendly and practical. This reaction fills in the missing part in transesterification reaction of phenols and provides an efficient approach to aryl esters, which are widely used in the synthetic and pharmaceutical industry.
A study on reactions of an alkynylsilane with oxone-KX (X = Cl, Br, I) and its one-pot transformation into an amide/ester
Sriramoju, Vinodkumar,Jillella, Raveendra,Kurva, Srinivas,Madabhushi, Sridhar
, p. 560 - 562 (2017/03/30)
Oxyhalogenation reactions of a variety of alkynylsilanes were studied using oxone as mild oxidant and KCl, KBr, and KI as halogen sources. In this study, reaction of an alkynylsilane with oxone-KX (X = Cl or Br) produced trichloromethyl/tribromomethyl ketones inhigh yields. Under similar conditions, however, reactions of alkynylsilanes with oxone-KI were found to give exclusively 1,2,2-triiodovinyl derivatives in high yields. In this study, new methods were deveoped for effcient one-pot tranformation of alkynylsilanes into amides and esters by reaction with amines and alcohols respectively via trihalomethyl ketone.
