Integration of a Four-Step Reaction into One-Pot under the Coexistence of Silica-Gel-Supported Acid and Base Reagents: Synthesis of Benzo- and Naphthothiophenes Using NaHSO4/SiO2 and Na2CO3/SiO2
reaction proceeded efficiently by introduction of starting materials and reagents in a single reaction vessel. The starting materials were very easy to handle and unpleasant smell of aryl thiols that were used in conventional methods could be avoided. Novel thirty-nine benzo- and naphthothiophenes were synthesized by this method in excellent to fair yields. A four-step synthesis of benzo- and naphthothiophenes
Novel deacylation of α-bromo-β-diketones using silica sulfuric acid (SSA) has been developed. Deacylation of 3-bromopentane-2,4-diones and 2-bromobutane-1,3-diones were carried out in the presence of SSA in dichloroethane under mild conditions to obtain the corresponding α-bromo ketones in good to excellent yields. SSA also promoted the Friedel–Crafts type alkylation of benzene with 3-(sec-alkyl)-2,4-pentanediones to give the corresponding triarylmethanes in high yields in benzene.
One-pot tandem three-step reaction has been developed by using supported reagents system. The synthesis of 2-aminothiazoles was selected for confirming the effectiveness of the method using supported reagents system. One-pot three-step reaction effectively proceeded, and the yield of the products is higher than that in step-wise process. (c) 2007 Elsevier Ltd. All rights reserved.
Simple Method for sp2–sp3 and sp3–sp3 Carbon–Carbon Bond Activation in 2-Substituted 1,3-Diketones
Simple and efficient methods were developed for sp(2)-sp(3) and sp(3)-sp(3) C-C bond-activation reactions of 2-substituted 1,3-diketones. 3-Substituted 3-bromopentane-2,4-diones were deacylated in the presence of an aromatic compound and a silica gel supported Bronsted acid containing sulfonic groups. The carbocation formed by cleavage of the sp(3)-sp(3) C-C bond of the dione alkylated the aromatic compound.
Visible‐Light‐Induced Radical Cascade Cyclization of <i>o‐</i>Diisocyanoarenes: Synthesis of Diethyl Benzo[<i>a</i>]phenazine‐6,6(5<i>H</i>)‐Dicarboxylate
A visible-light-induced radical cascade cyclization of ortho-diisocyanoarenes for the synthesis of diethyl benzo[a]phenazine-6,6(5H)-dicarboxylates has been developed. This process provides an efficient and convenient protocol for the construction of benzo[a]phenazine skeleton that widely present in biologically active molecules and pharmaceuticals. The reaction takes place under mild conditions and
已开发出用于合成苯并[ a ]吩嗪-6,6(5 H )-二羧酸二乙酯的邻二异氰芳烃的可见光诱导自由基级联环化。该过程为构建广泛存在于生物活性分子和药物中的苯并[ a ]吩嗪骨架提供了一种高效便捷的方案。该反应在温和的条件下进行,以中等至极好的收率获得产物。