An efficient bromination of alkenes using cerium(IV) ammonium nitrate (CAN) and potassium bromide

Nair, Vijay; Panicker, Sreeletha B.; Augustine, Anu; George, Tesmol G.; Thomas, Siji; Vairamani, M.

doi:10.1016/s0040-4020(01)00712-8

Cited by 97 publications

(43 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With this initial study completed, the synthesis of β-azido ketones was extended to several cyclopropanols 2-4. Both aryl-and alkyl-substituted cyclopropanols (1)(2)(3)(4) afforded corresponding β-azido ketones in good to high isolated yields (70-83%) as shown in Table 1 (entries 1, 5,9,13). Next, the CAN mediated strategy was employed to construct other carbon-heteroatom bonds including C-S, C-I, and C-Br.…”

mentioning

confidence: 99%

An Efficient and General Approach to β-Functionalized Ketones

et al. 2007

View full text Add to dashboard Cite

The oxidation of selected anions (N 3 − , SCN − , I − and Br − ) by ceric ammonium nitrate (CAN) in the presence of substituted cyclopropyl alcohols provides a novel approach to β-functionalized ketones.The protocol has a number of advantages including short reaction times, ease of reagent handling and mild, neutral reaction conditions. Overall, this method provides an alternative pathway to important starting materials and intermediates in organic synthesis.Ketones substituted in the β position are important starting materials in organic chemistry. Among this group, β-haloketones are extremely useful intermediates in organic synthesis and act as precursors to enones, annulated compounds, heterocyclic derivatives, and dicarbonyl products. 1 In spite of their importance as precursors to a large range of important intermediates, 2 only a few of methods have been developed to synthesize β-substituted ketones. 3 The synthesis of β-substituted ketones by 1,4-addition of HX (X = Cl, Br, I) or trimethylsilyl iodide to the corresponding enone are sometimes experimentally inconvenient since the use of reactive or moisture sensitive reagents are required. 3b, 3d More recent approaches to β-substituted ketones, while useful, provide access to a limited range of compounds. 4,5 As a consequence, the development of new synthetic methods offering a general approach for the introduction of diverse functionality to the beta position of a carbonyl group still constitutes a challenge in organic chemistry.Cerium(IV) ammonium nitrate (CAN) has found wide applications in carbon-heteroatom bond forming reactions in organic synthesis. 6 The reported carbon-heteroatom bond formations mediated with CAN include C-Br, C-I, C-S, C-N, and C-Se bonds. These reactions usually involve the generation of heteroatom-centered radicals from the oxidation of anions and addition of the heteroatom radicals to alkenes or alkynes.Based on this precedent, we reasoned that Ce(IV) oxidation of an anion in the presence of a cyclopropyl alcohol would provide a route to β-substituted ketones as shown in Scheme 1. Since cyclopropyl units are readily accessible via the Kulinkovich reaction, 7 the ring opening of cyclopropanols and the carbon-heteroatom bond formation mediated with CAN could provide a novel, efficient, and general approach to a variety of β-substituted ketones.The synthesis of substituted cyclopropyl alcohols 1-4 shown in Table 1 were carried out using the Kulinkovich reaction and provided good isolated yields in the range of 63-82%. In an initial experiment, sodium azide was chosen as the first anion to react with a cyclopropyl alcohol since oxidation of this anion with CAN has been previously reported. 8 Reaction of 1 with NaN 3 in the presence of 2 equivalents of CAN in methanol produced a moderate yield (50%) of the 3-azido-1-phenyl propanone along with dimer and nitrated products as side products.rof2@lehigh.edu. NIH Public Access NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptSince solvent is known to play...

show abstract

mentioning

confidence: 99%

An Efficient and General Approach to β-Functionalized Ketones

et al. 2007

View full text Add to dashboard Cite

show abstract

“…Bromination of alkenes to afford vicinal dibromides was effected by using potassium bromide and CAN in a two-phase system of water and dichloromethane; in solvents, such as methanol or acetonitrile, phenacyl bromide and 1,2-nitrato bromide were formed. 116 Efficient CAN mediated bromination and iodination at C-5 of uracil nucleosides has been achieved using catalytic amounts of CAN and potassium bromide in acetonitrile or DMF. 117 A stereoselective synthesis of 2-deoxy-2-iodo-a-manno-pyranosyl acetate by the CAN mediated addition of iodide to glycals has been reported recently by Roush et al 118 Iodination of a,b-unsaturated ketones and esters with iodine and CAN in methanol under reflux conditions afforded the corresponding b-methoxy a-iodoketones and esters in good yields 119 while in acetonitrile, b-hydroxy a-iodoketones and esters were obtained.…”

Section: Carbon-halogen Bond Formationmentioning

confidence: 99%

Recent advances in CAN mediated reactions in organic synthesis

Nair

Deepthi

2009

Tetrahedron

Self Cite

View full text Add to dashboard Cite

“…The oxidative bromination of aromatic compounds by either molecular bromine or by the hydrogen peroxide-bromide redox cycle leads to the ring bromination as it involves two electron redox mechanism. Whereas, interaction of bromide ion with one electron oxidants leads to the formation of bromine free radical which effects the side chain bromination [10] of organic substrates. Therefore, in continuation of our work on the oxidation of inorganic reductants by TBATB [11,12], the title reaction was investigated kinetically to understand the mechanism which was found to involve formation bromine free radical as a result of one electron reduction of TBATB by the reductant, vanadium(IV).…”

Section: Introductionmentioning

confidence: 99%

Kinetics and mechanism of vanadium(IV) oxidation by tetrabutylammonium tribromide

Kalantre

Maradur

Gokavi

2007

Transition Met Chem

View full text Add to dashboard Cite

The reaction between tetrabutylammonium tribromide(TBATB) and vanadium(IV) has been studied in 50% (v/v) acetic acid under second order conditions. The overall order of reaction is found to be two, unity in each reactant. The reaction involves two single-electron transfer steps generating bromine free radical in the first rate determining step. The test for the formation of free radicals in presence of added acrylonitrile was negative while added toluene increases the rate of the reaction considerably due to its conversion into benzyl bromide. The reaction is retarded by hydrogen ions as a result of protonation prior equilibria of the active reductant, vanadyl acetate. The oxidation of the vanadylsalen complex by TBATB proceeds more rapidly than that of vanadyl acetate but follows the similar kinetic behaviour. Considerable decrease in the entropy of activation of the reaction indicates formation of an ordered transition state between the two reactants and since the kinetic behaviour remains unaltered, even after the change in the ligand attached to the reductant, indicates an interaction between the reactants through the oxygen atom on the vanadyl ion.

show abstract

An efficient bromination of alkenes using cerium(IV) ammonium nitrate (CAN) and potassium bromide

Cited by 97 publications

References 16 publications

An Efficient and General Approach to β-Functionalized Ketones

An Efficient and General Approach to β-Functionalized Ketones

Recent advances in CAN mediated reactions in organic synthesis

Kinetics and mechanism of vanadium(IV) oxidation by tetrabutylammonium tribromide

Contact Info

Product

Resources

About