نتایج جستجو برای: bromination
تعداد نتایج: 805 فیلتر نتایج به سال:
A mild and efficient methodology for the bromination of phenols and alkenes has been developed utilizing visible light-induced photoredox catalysis. The bromine was generated in situ from the oxidation of Br(-) by Ru(bpy)3 (3+), both of which resulted from the oxidative quenching process.
An efficient and facile strategy has been developed for bromination of nucleosides using sodium monobromoisocyanurate (SMBI). Our methodology demonstrates bromination at the C-5 position of pyrimidine nucleosides and the C-8 position of purine nucleosides. Unprotected and also several protected nucleosides were brominated in moderate to high yields following this procedure.
A new protocol for the oxidative bromination of aminoanthracene-9,10-dione, which is highly deactivated towards the electrophilic substitution is investigated. The peracid, nonanebis(peroxoic acid), possesses advantages such as better stability at room temperature, it is easy to prepare and non-shock sensitiv as compared to the conventional peracids. The present protocol has a broad scope for t...
An unique long-range 1,7-bromination reaction is observed in gold(III) complexes of N-(aryl)imino functionalized N-heterocyclic carbene with the bromination occurring at two different carbon (sp2 and sp3) centers spatially separated by ca. 6.4 A but existing in extended conjugation to each other. In particular, the unusual distant 1,7-brominated gold(III) complexes [1-R-3-{N-(p-bromo-2,6-di-i-p...
Treatment of the protected and unprotected nucleosides with 1,3-dibromo-5,5- dimethylhydantoin in aprotic solvents such as CH(2)Cl(2), CH(3)CN, or DMF effected smooth bromination of uridine and cytidine derivatives at C-5 of pyrimidine rings as well as adenosine and guanosine derivatives at C-8 of purine rings. Addition of Lewis acids such as trimethylsilyl trifluoromethanesulfonate enhanced ef...
The graphite nanoplatelets (GNP) were treated by vapor-phase bromination. The increase in weight and atomic concentration of Br indicated the bromine uptake. The intercalation of Br between graphene layers of GNP was confirmed by the X-ray diffraction result, showing an increase in the interlayer spacing from 3.342 Å to 3.361 Å. Two types of bonds between C and Br were introduced simultaneously...
The human 8-oxoguanine DNA glycosylase OGG1 is involved in base excision repair (BER), one of several DNA repair mechanisms that may counteract the effects of chemo- and radiation therapy for the treatment of cancer. We envisage that potent inhibitors of OGG1 may be found among the 9-alkyl-8-oxoguanines. Thus we explored synthetic routes to 8-oxoguanines and examined these as OGG1 inhibitors. T...
The bromination of a series of cyclohexenyl substituted secondary amines 1a-i has been investigated using Br2, PHT and NBS. In the case of Br2 and NBS the secondary amines preferentially undergo N-bromination. In contrast, PHT cleanly affords the products of alkene dibromination. In the case ofBr2 the N-bromo species then give the products of alkene dibromination, albeit less efficiently. On su...
BACKGROUND The dihydroazulene (DHA)/vinylheptafulvene (VHF) system (with two cyano groups at C1) functions as a photo-/thermoswitch. Direct ionic bromination of DHA has previously furnished a regioselective route to a 7,8-dibromide, which by elimination was converted to a 7-bromo-substituted DHA. This compound has served as a central building block for functionalization of the DHA by palladium-...
The two most common halogenation reactions are chlorination and bromination. The addition of these halogens to alkenes yields 1,2-dihalides. Chlorinations reactions are used to synthesize over 6 million tons per year of ethylene dichloride (1,2-dichloroethane) for use as a solvent and for subsequent polymerization to produce poly(vinylchloride) known more commonly as PVC which is used for plumb...
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