Synthesis of Indazoles by the [3+2] Cycloaddition of Diazo Compounds with Arynes and Subsequent Acyl Migration
作者:Zhijian Liu、Feng Shi、Pablo D. G. Martinez、Cristiano Raminelli、Richard C. Larock
DOI:10.1021/jo702062n
日期:2008.1.1
The [3+2] cycloaddition of a variety of diazocompounds with o-(trimethylsilyl)aryl triflates in the presence of CsF or TBAF at room temperature provides a very direct, efficient approach to a wide range of potentially biologically and pharmaceutically interesting substituted indazoles in good to excellent yields under mild reaction conditions. Simple diazomethane derivatives afford N-unsubstituted
Nitrogen-Based Lewis Acids: Synthesis and Reactivity of a Cyclic (Alkyl)(Amino)Nitrenium Cation
作者:Jiliang Zhou、Liu Leo Liu、Levy L. Cao、Douglas W. Stephan
DOI:10.1002/anie.201713118
日期:2018.3.19
crystalline cyclic (alkyl)(amino)nitrenium cation 2 features cationic nitrogen atom with a smaller HOMO–LUMO gap compared to that of a 1,2,3‐triazolium 5 (an N‐heterocyclic nitrenium cation). The low‐lying LUMO of 2 results in an enhanced electrophilicity, which allowed for the formation of Lewis adducts with neutral Lewis bases, such as Me3P, nBu3P, and IiPr. The N‐based Lewis acid 2 also forms an FLP with
室温稳定的结晶环状(烷基)(氨基)氮阳离子阳离子2具有比1,2,3-三唑鎓5(N杂环nitr阳离子)小的阳离子氮原子,其HOMO-LUMO间隙更小。较低的LUMO为2导致亲电性增强,这允许形成具有中性路易斯碱的路易斯加合物,例如Me 3 P,n Bu 3 P和I i Pr。N基路易斯酸2也与t Bu 3 P形成FLP,但随后与(PrS)2反应切割SS键。实验和理论结果均表明2的路易斯酸度比其N 3类似物强。