Search results for "halogenation"

Oxidative halogenation of substituted pyrroles with Cu(II). PartIV.Bromination of 2-(2′-hydroxybenzoyl)pyrrole. A new synthesis of bioactive analogs …

1994

The selective bromination with copper(II) bromide of the pyrrole ring in 2-(2'-hydroxybenzoyl)pyrrole (II) in the heterogeneous phase is des- cribed giving in almost quantitative yield the 4,5-dibromo derivative (VI). The subsequent introduction of halogen into the phenol moiety was observed when the reaction was perfomed in the homogeneous phase with an excess of halogenating agent. The pentabromo derivative (IX), a com- pound very active against Staphylococcus aureus (mic=17 nmoles per dm -3 ), was obtained by exhaustive bromination of the title compound. Poor yields of chloro derivatives of (II) were obtained by reaction of the parent compound with copper(II) chloride

2017

The title compound, C12H14Br2, was prepared by bromination/dehydrobromination ofE,E,Z-cyclododecatriene. The crystal is composed ofC2-symmetrical molecules with anEconformation of the bromoalkene fragments and nearly linear alkyne units. The torsion angles in the ring suggest significant ring strain.

Identification of the Iodination and Bromination Products of 3-Hydroxybenzaldehyde: Preparation of 5-Hydroxy-2-iodobenzaldehyde

2017

The monohalogenation products of 3-hydroxybenzaldehyde (1) are useful synthons for the preparation of more complex molecules.1–4 For example, the introduction of a halogen allows the use of a Suzuk...

Der nachweis der kettenstruktur von aus p-kresol und formaldehyd aufgebauten mehrkernverbindungen. I. Durch verschiedene synthese und identifizierung…

1962

In ubersichtlicher, mehrfacher Synthese werden homologe Mehrkernverbindungen aufgebaut, die aus uber Methylenbrucken verbundenen p-Kresolbausteinen bestehen (Novolak-Struktur). Die verschiedenen, zu einer Mehrkernverbindung fuhrenden Synthesen geben identische Verbindungen. Die Kettenstruktur dieser Mehrkernverbindungen kann durch kettenanaloge Enthalogenierungen, durch geeignete Kondensationen (Gl. (1)) sowie durch entsprechende Substitutionsbanden in den IR-Spektren der Verbindungen nachgewiesen werden. By means of rational, multiple syntheses, homologous polynuclear compounds were prepared, consisting of p-cresol units linked by methylene bridges (Novolac structure). The different ways o…

ChemInform Abstract: One-Pot Synthesis of Pyrrole-2-carboxylates and -carboxamides via an Electrocyclization/Oxidation Sequence.

2015

An electrocyclic ring closure is the key step of an efficient one-pot method for the synthesis of pyrrole-2-carboxylates and -carboxamides from chalcones and glycine esters or amides. The 3,4-dihydro-2H-pyrrole intermediates generated in situ are oxidized to the corresponding pyrroles by stoichiometric oxidants or by catalytic copper(II) and air in moderate to high yields. A wide range of functional groups are tolerated, and further combination with an in situ bromination gives access to polyfunctional pyrrole scaffolds.

ChemInform Abstract: Iodocyclization of o-Alkynylbenzamides Revisited: Formation of Isobenzofuran-1(3H)-imines and 1H-Isochromen-1-imines Instead of …

2013

Remarkably, isobenzofuran and benzopyran derivatives are obtained by the title reaction and not as described in earlier publications five- or six-membered lactams.

Challenges in the Electrochemical Synthesis of Si 2 Cl 6 Starting from Tetrachlorosilane and Trichlorosilane

2022

ChemInform Abstract: Elemental Bromine Production by TiO2Photocatalysis and/or Ozonation.

2016

Significant production of elemental bromine (Br2 ) was observed for the first time when treating bromide containing solutions at acidic pH, with TiO2 photocatalyst, ozone, or a combination thereof. Br2 selectivities up to approximately 85 % were obtained and the corresponding bromine mass balance values satisfied. The process is general and may be applied at a laboratory scale for green bromination reactions, or industrially as a cheap, safe, and environmentally sustainable alternative to the currently applied bromine production methods.

ChemInform Abstract: Acid-Mediated Reaction of Bis(pyridine)iodonium(I) Tetrafluoroborate with Aromatic Compounds. A Selective and General Iodination…

2010

Reaction of aromatic compounds with bis(pyridine)iodonium(I) tetrafluoroborate (IPy2BF4) in the presence of HBF4 or CF3SO3H in CH2Cl2 at room temperature furnishes monoiodo derivatives with excellent regioselectivity and yields. Use of either acid gives comparable results with activated aromatics, whereas CF3SO3H is much more effective in the iodination of deactivated aromatics. © 1993 American Chemical Society.

Oxidative halogenation of substituted pyrroles with cu(II). Part I. Bromination of some 3-acetylpyrroles

1990

3-Acetylpyrroles are brominated with copper(II) bromide. The reaction afforded almost quantitatively only nuclear monobromination. Evidence for the structures of final compounds was by mass spectrometry, 1 H-nuclear magnetic resonance, ir, and elemental analysis