The charge‐accelerated aza‐Claisen rearrangement of ammonium salts serves as a key step in the construction of complex nitrogen‐containing molecules. However, much less attention has been paid to the aromatic aza‐Claisen rearrangement than to the aliphatic one. Herein, we report an unprecedented aromatic aza‐Claisen rearrangement of arylpropargylammonium salts, generated in situ from arynes and tertiary
One-Pot Synthesis of Polysubstituted Imidazoles via Sequential Staudinger/aza-Wittig/Ag(I)-Catalyzed Cyclization/Isomerization
作者:Jun Xiong、Xiao Wei、Zi-Ming Liu、Ming-Wu Ding
DOI:10.1021/acs.joc.7b02606
日期:2017.12.15
A new one-pot preparation of polysubstituted imidazoles by a Staudinger/aza-Wittig/Ag(I)-catalyzed cyclization/isomerization has been developed. The easily accessible propargylazide derivatives reacted with triphenylphosphine, isocyanates, and amines sequentially to produce the fully substituted imidazoles in good overall yields in the presence of catalytic amount of AgNO3/DMAP.
Intercepting the Banert cascade with nucleophilic fluorine: direct access to α-fluorinated <i>N</i>H-1,2,3-triazoles
作者:J. R. Alexander、P. V. Kevorkian、J. J. Topczewski
DOI:10.1039/d1cc01179k
日期:——
The treatment of propargylic azides with silver(I) fluoride in acetonitrile was found to yield α-fluorinated NH-1,2,3-triazoles via the Banert cascade. The reaction was regioselective and the products result from an initial [3,3] rearrangement. The reaction is demonstrated on >15 examples with yields ranging from 37% to 86%.
An efficient, unified approach for the synthesis of β-carbolines, γ-carbolines, and other fused azaheteroaromatics has been realized under metal-free conditions, from propargylic amines and (hetero)aromatic aldehydes. This unified strategy provides β- and γ-carbolines as well as a range of fused azaheteroaromatics with a broad substrate scope and excellent functional group compatibility. The formal
Palladium(II)-Catalyzed Directed <i>anti-</i>Hydrochlorination of Unactivated Alkynes with HCl
作者:Joseph Derosa、Annabelle L. Cantu、Mark N. Boulous、Miriam L. O’Duill、Joshua L. Turnbull、Zhen Liu、Daizy M. De La Torre、Keary M. Engle
DOI:10.1021/jacs.7b00892
日期:2017.4.12
A regioselective anti-hydrochlorination of unactivated alkynes is reported. The reaction utilizes in situ generated HCl as the source of both the Cl- and H+ and is catalyzed by palladium(II) acetate, with loadings as low as 25 ppm. Removable picolinamide and 8-aminoquinoline bidentate directing groups are used to control the regioselectivity of the chloropalladation step and stabilize the resulting
报道了未活化炔烃的区域选择性抗氢氯化作用。该反应利用原位生成的 HCl 作为 Cl- 和 H+ 的来源,并由乙酸钯 (II) 催化,负载量低至 25 ppm。可去除的吡啶甲酰胺和 8-氨基喹啉二齿导向基团用于控制氯钯化步骤的区域选择性,并稳定所得的链烯基钯 (II) 中间体,用于随后的原脱钯反应。该方法提供了以优异的产率和高区域选择性获得广泛的取代链烯基氯的途径。这种转化的产物通过 Stille 偶联成功衍生为多种三取代烯烃产物。进行了反应进程动力学分析,揭示了该催化过程的可能机制。