Addition of bromine to 2-methyl-2-azabicyclo[2.2.1]hept-5-ene

Addition of bromine to 2-methyl-2-azabicyclo[2.2.1]hept-5-ene was studied. Unexpectedly, 3-bromo-1-methyl-1-azoniatricyclo[2.2.1.0^2,6]heptane tribromide was isolated rather than the product of bromine addition to the double bond. The former reacted with the starting alkene in a polar solvent to form the corresponding monobromide.     

Bromination of Substituted 5H-Imidazo[1,2-b]-1,2,4-triazepin-4-ones and -thiones

The reactions of substituted 5H-imidazo[1,2-b]-1,2,4-triazepin-4-ones and -thiones with bromine and N-bromosuccinimide have been studied. Derivatives of 3- and 8-bromo-, 3,8-dibromoimidazo[1,2-b]-1,2,4-triazepine and 5H-2-bromomethyl-3-methyl-7,8-diphenylimidazo[1,2-b]-1,2,4-triazepin-4-one are formed, depending on the degree of substitution, the nature of the brominating agent, and the reaction conditions.     

溴化铜对6-甲氧基-2-酰基萘的选择性溴化反应

甲氧基酰基萘;甲氧基溴酰基萘;溴化铜对6-甲氧基-2-酰基萘的选择性溴化反应     

Synthesis of Conjugated Systems Based on 3-(5-Methylfur-2-yl)-2-(3-oxobutyl)benzofurans

Methods were developed for the synthesis of 3-butyl-2-(3-oxobutenyl)benzofurans and 3-(3-furylbenzofuran-2-yl)acrylic acids on the basis of 3-furyl-2-(3-oxobutyl)benzofurans.     

Synthesis and Stereochemistry of Novel Dibrominated 1,5-Dioxaspiro[5.5]undecane Derivatives

Summary.  The synthesis and stereochemistry of new dibrominated spiro-1,3-dioxane derivatives are reported. Investigations by means of NMR methods and single crystal X-ray diffraction for two compounds revealed the high regio- and diastereoselectivity of the bromination reaction of some new spiro-1,3-dioxanes and the asymmetric induction of the chiral carbon atom located in the spiro skeleton. Received July 13, 1999. Accepted October 21, 1999     

Electrophilic aromatic substitution regioselectivity for benzene derivatives in terms of cationic localization energies from semiempirical quantum chemical computations

Cationic localization energies (Λ⁺) for the interaction of monosubstituted benzenes with nitronium cation have been computed by the PM3 method. Yields (Y) of nitration isomeric products correlate linearly with the Λ⁺ values. The lnY=a+bΛ⁺ expressions agree both with Arrhenius equation and with linear free energy relationships.     

Ultrasound-Assisted Synthesis of Fluorescent Azatetracyclic Derivatives: An Energy-Efficient Approach

We report here an energy-efficient and straight synthesis of two new classes of derivatized fluorescent azatetracycles under ultrasound (US) irradiation. A first class of azatetracyclic compounds was synthesized by heterogeneous catalytic bromination of the α-keto substituent attached to the pyrrole moiety of the tetracyclic cycloadducts, while for the second, one class was synthesized by nucleophilic substitution of the bromide with the azide group. Comparative with conventional thermal heating (TH) under US irradiation, both types of reactions occur with substantially higher yields, shortened reaction time (from days to hours), lesser energy consumed, easier workup of the reaction, and smaller amounts of solvent required (at least three to five-fold less compared to TH), which make these reactions to be considered as energy efficient. The derivatized azatetracycle are blue emitters with λmax of fluorescence around 430–445 nm. A certain influence of the azatetracycle substituents concerning absorption and fluorescent properties was observed. Compounds anchored with a bulky azide group have shown decreased fluorescence intensity compared with corresponding bromides.     

2-溴-3-(1H-吲哚-3)-N-甲基马来酰亚胺的合成

以琥珀酰亚胺为起始原料,经过溴化、甲基化后再与吲哚溴化镁加成反应合成了2-溴-3-(1H-吲哚-3)-N-甲基马来酰亚胺,总收率44.8%,其结构经1H NMR和IR确证.     

Direct and regioselective iodination and bromination of benzene, naphthalene and other activated aromatic compounds using iodine and bromine or their sodium salts in the presence of the Fe(NO3)3·1.5N2O4/charcoal system

Direct and regioselective iodination and bromination of benzene, naphthalene and other activated aromatic compounds with iodine and bromine or their sodium salts proceed well in the presence of Fe(NO₃)₃·1.5N₂O₄/charcoal in CH₂Cl₂ at room temperature.     

Nonisothermal thermogravimetry of polymers

The model of weight loss taking place in each step of a scheme of consecutive reactions was applied to nonisothermal thermogravimetric records of bromomethylated poly(2,6-dimethyl-1,4-phenylene oxide). The release of HBr was found to be faster in air than in nitrogen. A significant reduction in the apparent activation energy of dehydrobromination as compared with decomposition of the nonbrominated polymer was ascribed not only to a reduction in the activation energy of the initiation reaction, but also to an increase in the order of the termination reaction (from 1 for the nonbrominated polymer to 2 for the highly brominated polymer).