- The first syntheses of 3-bromofascaplysin, 10-bromofascaplysin and 3,10-dibromofascaplysin-marine alkaloids from Fascaplysinopsis reticulata and Didemnum sp. by application of a simple and effective approach to the pyrido[1,2-a:3,4-b′]diindole system
-
A simple and practical approach for the synthesis of the marine sponge pigment fascaplysin was used for the total syntheses of its natural derivatives, the marine alkaloids 3-bromofascaplysin, 10-bromofascaplysin, and 3,10-dibromofascaplysin. The conditions of each step were revised, and as a result these compounds were produced by identical procedures with total yields of 40-43%.
- Zhidkov, Maxim E.,Baranova, Olga V.,Balaneva, Nadezhda N.,Fedorov, Sergey N.,Radchenko, Oleg S.,Dubovitskii, Sergey V.
-
-
Read Online
- Reactivity of alkali and alkaline earth metal tetrafluorobromates towards aromatic compounds and pyridine
-
The bromination activity of tetrafluorobromates of alkali and alkali-earth metals increases in the order KBrF4, CsBrF4, RbBrF4and Ba(BrF4)2. The most active tetrafluorobromate—Ba(BrF4)2is able to selectively brominate the deactivated aromatic compounds nitrobenzene and 4-nitrotoluene, but not the activated compounds benzene and toluene. In all cases bromination of methyl groups of methylbenzenes does not occur. Ba(BrF4)2forms the known complex C6H5N·BrF3when reacted with pyridine. Due to dilution by inert BaF2, this pyridine-based complex is air stable and can be considered as safer and more convenient reagent in comparison with the original fluorobromates; it can selectively brominate benzene and toluene in contrast with tetrafluorobromates.
- Sobolev, Vasily I.,Filimonov, Victor D.,Ostvald, Roman V.,Radchenko, Vyacheslav B.,Zherin, Ivan I.
-
p. 120 - 123
(2016/11/17)
-
- PROCESS FOR THE PREPARATION OF 4-BROMOPHENYL DERIVATIVES
-
Disclosed is a process for the preparation of a mixture of 4-bromophenyl derivatives (compound of formula (2)) and 2,4-dibromophenyl derivatives (compound of formula (3)) comprising the steps of [1] reacting in a two-phase (liquid-liquid) system a bromide containing source with a phenyl derivative (formula (1)) in the presence of an excess of an oxidizing agent, an acid, and optionally a catalyst selected from vanadium pentoxide and ammonium heptamolybdate forming 4-bromo- (compound of formula (2)) and 2,4-dibromo derivatives (compound of formula (3)) and as intermediate product the 2-bromo derivative (compound of formula (4)) which reacts in step [2] to the 2,4-dibromo derivative (formula (3)) according to the following reaction scheme 2 wherein R1 is hydroxy; C1-C5alkoxy; or -NR2R3; and R2 and R3 independently from each other are hydrogen; or C1-C5alkyl.
- -
-
Page/Page column 10-11
(2010/04/03)
-
- Catalytic Sandmeyer bromination
-
An efficient catalyst system for Sandmeyer bromination is proposed. Aryl bromides and dibromides can be obtained with excellent yield by this synthetic protocol. Georg Thieme Verlag Stuttgart.
- Beletskaya, Irina P.,Sigeev, Alexander S.,Peregudov, Alexander S.,Petrovskii, Pavel V.
-
p. 2534 - 2538
(2008/03/13)
-
- Halogenation of Aromatic Compounds by N-chloro-, N-bromo-, and N-iodosuccinimide
-
An efficient and mild method for the halogenation of aromatic compounds using N-chloro-, N-bromo-, and N-iodosuccinimide in the presence of NH 4NO3 or FeCl3 in acetonitrile was developed.
- Tanemura, Kiyoshi,Suzuki, Tsuneo,Nishida, Yoko,Satsumabayashi, Koko,Horaguchi, Takaaki
-
p. 932 - 933
(2007/10/03)
-
- Synthesis, absorption and luminescence of a new series of soluble distyrylbenzenes featuring cyano substituents at the peripheral rings
-
The synthesis of a complete series of nine soluble distyrylbenzenes (DSBs) with two (2a-c) and four cyano groups (1a-f) attached to the peripheral aromatic rings is reported. They were prepared by the Wittig reaction and characterized by 1H and 13C NMR, FT-IR, UV/Vis, PL, EL, mass spectra, and elemental analysis. The optical properties have been studied in detail to monitor structure-luminescence relationships as a function of the position of the cyano moieties. The DSBs with cyano substituents show bathochromic shifts in their absorption spectra when compared to the parent DSB (30). The extent of this red-shift depends on electronic and steric factors. The bis(p-cyano)-substituted compound 2c exhibits a small Stokes shift and a remarkably high quantum yield of ψF = 0.6-0.8 in the solid state. All the new distyrylbenzenes show electroluminescence when employed in devices with an ITO/PcCu/DSB/Al configuration and with colors ranging from red to green.
- Schweikart, Karl-Heinz,Hanack, Michael,Lueer, Larry,Oelkrug, Dieter
-
p. 293 - 302
(2007/10/03)
-
- DECOMPOSITION OF (NiRR'L2) COMPLEXES INDUCED BY BROMINE OR ANODIC OXIDATION
-
A study has been made of the decomposition of the compounds t-(NiRR'L2) (L=PMe2Ph and PEt3; R=aryl or vinyl groups) and (Ni(mes)(o-tol)bipy) (mes=mesityl) oxidatively induced either by electrochemical means or by bromine.No organometallic compound of Ni(III) was isolated in the above reactions, but a pentacoordinate intermediate of Ni(III) is postulated.Breakdown takes place readily after the Ni(III) intermediate is formed.If the decomposition is induced is induced electrochemically, the intermediate decomposes giving only the coupling product R-R'.When bromine is used as the oxidizing agent, the Ni(III) intermediate is only formed if coordination to the central atom is allowed by the volume of the ligands.Thus, (Ni(C2Cl3)(mes)(PMe2Ph)2) dos not decompose at all, and only (Ni(C2Cl3(mesBr2)(PMe2Ph)2) is obtained.The intermediate ' Ni(III)RR'BrL2' undergoes reductive elimination to give R-R', RBr and R'Br.The formation of the products R-R'is increasingly favoured the greater the electronegativity of the organic ligands.The reductive elimination giving RBr takes place more readily the greater the electronegativity of the organic ligand R.The product of the reductive elimination reaction is 'Ni(I)Br', 'Ni(I)R', or 'Ni(I)R'', which in the presence of bromine give Ni(2+), (NiBr(RBr)L2), phosphonium salts, RBr, and R'Br.
- Coronas, Juan M.,Muller, Guillermo,Rocamora, Mercedes
-
p. 227 - 236
(2007/10/02)
-
- Process for the preparation of bromoarylacetylene and aryldiacetylene precursors
-
Bromoarylacetylenes such as m-bromophenylacetylene and certain precursors to such bromoarylacetylene are prepared by reacting an aryldibromide with a substituted terminal acetylene compound containing at least three carbon atoms and a hydroxy group on the carbon atom adjacent to the acetylene group in the presence of a dialkyl or trialkyl amine solvent and a catalyst system consisting of a palladium complex containing two halogen moieties and two tri-substituted phosphine moieties. Additional triphenylphosphine can be added. A cuprous iodide promoter is also employed in the reaction sequence. The bromoarylacetylenes can be reacted with a substituted terminal acetylene compound as defined using the same catalyst system as defined to produce the corresponding aryldihydroxy substituted acetylenes. Certain bromophenylhydroxy substituted acetylenes are claimed as new compositions.
- -
-
-
