Challenges associated with the synthesis of unusual o-carboxamido stilbenes by the Heck protocol: Intriguing substituent effects, their toxicological and chemopreventive implications
Intramolecular 1,5-H transfer reaction of aryl iodides through visible-light photoredox catalysis: a concise method for the synthesis of natural product scaffolds
The intramolecular 1,5-H transfer reaction of the aryl radicals generated from unactivited aryl iodides by photocatalysis is described. The features of this transformation are operational simplicity, excellent yields, mild reaction...
catalysis of CuI/1H-pyrrole-2-carboxylic acid. The coupling products underwent oxidation to afford the azo compounds, which were subjected to deprotection with TFA and in situ cyclization to give 1,2,4-benzotriazines.
Dibrominative Spirocyclization of 2-Butynolyl Anilides: Synthesis of <i>gem</i>-Dibromospirocyclic Benzo[<i>d</i>][1,3]oxazines and Their Application in the Synthesis of 4<i>H</i>-Furo[3,2-<i>b</i>]indoles
The combination of catalytic aqueous hydrochloricacid (HCl) and N-bromosuccinimide (NBS) generated electrophilic brominemonochloride (BrCl), which readily induced spiroannulation of 2-alkynolyl anilides (n = 1–3) to form gem-dibromospirocyclic benzo[d][1,3]oxazines in up to 92% yield. The reaction occurred under mild and metal-free conditions using EtOAc as a green solvent. The resulted spirocyclic
催化盐酸水溶液(HCl)和N-溴代琥珀酰亚胺(NBS)的结合产生亲电的一氯化溴(BrCl),该溶液很容易诱导2-炔基苯甲酰胺(n = 1-3)的螺环化反应,形成宝石-二溴螺环苯并[ d ] [1,3]恶嗪的产率高达92%。反应在温和且无金属的条件下进行,使用EtOAc作为绿色溶剂。所得的螺环产物包含苯并[ d ] [1,3]恶嗪,其既可以用作药效基团,也可以用作合成前体。此外,当前协议允许毫不费力地引入sp 3 - gem-二溴碳与空间要求很高的螺环中心相邻。这些螺旋杂环(n = 1)被证明具有通用性,并且操作方便。这些螺环的碱促进的脱溴化芳构化以极好的收率掩盖了稀有的和合成上有用的2-芳基-3-溴呋喃。这些3-溴呋喃是分子内Ullmann C–N键偶合以构建难以制备的4 H -furo [3,2- b ]吲哚的合适底物。另外,当前的方案是灵活的并且可适应于制备宝石-二氯化物变体。
Synthesis of <i>N</i>-Acylcarbazoles through Palladium-Catalyzed Aryne Annulation of 2-Haloacetanilides
作者:Chun Lu、Nataliya A. Markina、Richard C. Larock
DOI:10.1021/jo3021727
日期:2012.12.21
N-Acylcarbazoles have been synthesized in moderate to good yields by the annulation of in situ generated arynes with 2-haloacetanilides in the presence of a palladium catalyst and CsF. Both C–C and C–N bonds are formed simultaneously, and a variety of functional groups are tolerated in this reaction.
of benzoxazolesvia intramolecularcyclization of ortho -haloanilides using heteroge-neous copper fluorapatite catalyst is described. A variety of ortho -haloanilides (iodo-, bromo- and chloroanilides) were cyclized to thecorresponding benzoxazoles, demonstrating the versatility of thereaction. Key words: copper fluorapatite catalyst, ortho -haloanilides, in-tramolecular cyclization, heterogeneous catalyst