通过Rh(III)催化的2-芳基-2 H-吲唑与α-重氮羰基化合物的无氧化剂环氧化反应选择性合成5,6-二取代和5-取代的吲唑并[2,3- a ]喹啉是报告。以2-芳基-2 H-吲唑为底物,α-重氮羰基化合物可作为C2合成子,通过Rh(III)催化[ 5,6-二取代的吲唑并[2,3- a ]喹啉] [4 +2]。另一方面,当使用2-芳基-3-甲酰基-2 H-吲唑类作为底物时,α-重氮羰基化合物转变为C1合成子,需要经历更复杂的[5 + 1]环化工艺来提供5位取代的吲哚并[2,3- a ]喹啉。
Charge Migration in Dicationic Electrophiles and Its Application to the Synthesis of Aza-polycyclic Aromatic Compounds
摘要:
Superacid-promoted reactions of dicationic electrophiles have been studied, and the positive charge centers are found to migrate apart in a predictable manner. Using isotopic labeling the charge migration is found in one system to occur through successive deprotonation-reprotonation steps. The charge migration chemistry is the basis for new general synthetic route to aza-polycyclic aromatic compounds.
A straightforward and efficient method for the preparation of 2-aryl-2H-indazoles from ortho-alkyl substituted azoxybenzenes is presented. The reaction proceeds through base-catalyzed benzyl C–H deprotonation and cyclization to afford 2-aryl-2H-indazoles in good yields. This synthetic strategy can be applied to the construction of several fluorescent and bioactive molecules.
operationally simple method for the regioselective synthesis of 2-aryl-substituted 2H-indazoles is reported. The Pd-catalyzed reaction between easily available 2-bromobenzyl bromides and arylhydrazines employing Cs2CO3 as the base and t-Bu3PHBF4 as the ligand in DMSO at 120 °C in a sealed tube delivers the 2-substituted-2H-indazoles in a single synthetic step with yields up to 79%. The newmethod is based on
报道了直接和操作简单的方法用于区域选择性合成2-芳基取代的2 H-吲唑。容易获得的2-溴苄基溴化物和芳基肼采用铯之间的Pd-催化反应2 CO 3作为碱和吨-Bu 3 PHBF 4作为在密封管中120℃下在DMSO中配体递送2-取代- 2 ħ -吲唑在单个合成步骤中的收率高达79%。该新方法基于区域选择性的分子间N-苄基化,然后进行分子内N-芳基化和氧化。
Synthesis of 2<i>H</i>-Indazoles by the [3 + 2] Dipolar Cycloaddition of Sydnones with Arynes
作者:Yuesi Fang、Chunrui Wu、Richard C. Larock、Feng Shi
DOI:10.1021/jo201605v
日期:2011.11.4
A rapid and efficient synthesis of 2H-indazoles has been developed using a [3 + 2] dipolar cycloaddition of sydnones and arynes. A series of 2H-indazoles have been prepared in good to excellent yields this protocol, and subsequent Pd-catalyzed coupling reactions can be applied to the halogenated products to generate a structurally diverse library of indazoles.