Electrochemical oxidation of hydroquinone（1a） has been studied in the presence of 6-methyl-2-thiouracil（3a） and 6-propyl-2-thiouracil（3b） as nucleophiles in a DMF/buffer mixture,using cyclic voltammetry and cont...Electrochemical oxidation of hydroquinone（1a） has been studied in the presence of 6-methyl-2-thiouracil（3a） and 6-propyl-2-thiouracil（3b） as nucleophiles in a DMF/buffer mixture,using cyclic voltammetry and controlled-potential coulometry.The results indicated that the p-quinone（2a） derived from 1a participates in a 1 4-Michael addition reaction with the thiouracil derivatives（3a–b） to form the corresponding hydroquinonethioether derivatives（6a–6b）.The electrosynthesis of these compounds（6a–b） has been successfully performed on carbon rod electrodes in an undivided cell in good yield and purity.展开更多
The electrochemistry of di-μ-oxo-dimanganese complex was investigated. It was found that no redox peak was observed in the cyclic voltammogram (CV) of the complex at the bare gold electrode, but at thiouracil-modifie...The electrochemistry of di-μ-oxo-dimanganese complex was investigated. It was found that no redox peak was observed in the cyclic voltammogram (CV) of the complex at the bare gold electrode, but at thiouracil-modified gold electrode, a pair of redox peaks were observed showing that thiouracil can promote the proton-coupled electron transfer reaction of the complex.展开更多
A general method for the solid phase synthesis of hydro-uracils and thiouracils is described. Resino ester 2 reacts with various primary amines to give secondary amines 3, which are converted to the resino ureas (thio...A general method for the solid phase synthesis of hydro-uracils and thiouracils is described. Resino ester 2 reacts with various primary amines to give secondary amines 3, which are converted to the resino ureas (thioureas) 4 by treatment with isocyanates (isothiocyanates). Preparation of the hydro-uracils and thiouracils 5 is achieved by acidic cyclization-cleavage from the resin. The synthesis is designed to be amenable for structure based library approach to photosystem II D1 protein inhibitors.展开更多
The interaction of Cd2＋ with uracil,2-thiouracil,4-thiouracil and 2,4-dithiouracil have been investigated by the density functional theory（DFT） calculations.For uracil and 2,4-dithiouracil,where the two basic sites...The interaction of Cd2＋ with uracil,2-thiouracil,4-thiouracil and 2,4-dithiouracil have been investigated by the density functional theory（DFT） calculations.For uracil and 2,4-dithiouracil,where the two basic sites are the same,Cd2＋ attachment to the heteroatom at position 4 is preferred.However,for the systems where both types of basic centers,a carbonyl and a thiocarbonyl groups,are present,Cd2＋ association with sulfur is favorable.The enhanced stability of these enolic and thiol forms comes from Cd2＋ interaction with two basic sites simultaneously,which thereby triggers a significant aromatization of the ring.More significantly,the Cd2＋ binding energy with uracil and its thio-derivatives is larger than the tautomerization barriers connecting the diketo-like forms with the corresponding enolic-like tautomers.Consequently,when associated with Cd2＋,all tautomers are energetically accessible and should be observed in the gas phase.展开更多
基金Semnan University Research Council for financial supports of this work
文摘Electrochemical oxidation of hydroquinone（1a） has been studied in the presence of 6-methyl-2-thiouracil（3a） and 6-propyl-2-thiouracil（3b） as nucleophiles in a DMF/buffer mixture,using cyclic voltammetry and controlled-potential coulometry.The results indicated that the p-quinone（2a） derived from 1a participates in a 1 4-Michael addition reaction with the thiouracil derivatives（3a–b） to form the corresponding hydroquinonethioether derivatives（6a–6b）.The electrosynthesis of these compounds（6a–b） has been successfully performed on carbon rod electrodes in an undivided cell in good yield and purity.
文摘The electrochemistry of di-μ-oxo-dimanganese complex was investigated. It was found that no redox peak was observed in the cyclic voltammogram (CV) of the complex at the bare gold electrode, but at thiouracil-modified gold electrode, a pair of redox peaks were observed showing that thiouracil can promote the proton-coupled electron transfer reaction of the complex.
文摘A general method for the solid phase synthesis of hydro-uracils and thiouracils is described. Resino ester 2 reacts with various primary amines to give secondary amines 3, which are converted to the resino ureas (thioureas) 4 by treatment with isocyanates (isothiocyanates). Preparation of the hydro-uracils and thiouracils 5 is achieved by acidic cyclization-cleavage from the resin. The synthesis is designed to be amenable for structure based library approach to photosystem II D1 protein inhibitors.
基金supported by the NNSFC (20973174 and 91122015)the Young Scientist Fund of NSFC (81001403)the Youth Innovation Fund,Institute Key Program (SZD08003) of FJIRSM
文摘The interaction of Cd2＋ with uracil,2-thiouracil,4-thiouracil and 2,4-dithiouracil have been investigated by the density functional theory（DFT） calculations.For uracil and 2,4-dithiouracil,where the two basic sites are the same,Cd2＋ attachment to the heteroatom at position 4 is preferred.However,for the systems where both types of basic centers,a carbonyl and a thiocarbonyl groups,are present,Cd2＋ association with sulfur is favorable.The enhanced stability of these enolic and thiol forms comes from Cd2＋ interaction with two basic sites simultaneously,which thereby triggers a significant aromatization of the ring.More significantly,the Cd2＋ binding energy with uracil and its thio-derivatives is larger than the tautomerization barriers connecting the diketo-like forms with the corresponding enolic-like tautomers.Consequently,when associated with Cd2＋,all tautomers are energetically accessible and should be observed in the gas phase.
