作者:Bin Dai、Ping Liu、Jing He、Yueting Wei、Yijiao Feng、Chuntian Li
DOI:10.1055/a-1684-0308
日期:2022.4
A direct C–H halogenation of 3-aryl-1H-pyrazol-5-amines using N-halogenosuccinimides (NXS; X = Br, I, Cl) in dimethyl sulfoxide at room temperature has been developed. This transformation provides an effective metal-free protocol for the synthesis of novel 4-halogenated pyrazole derivatives with moderate to excellent yields. The method utilizes NXS reagents as cheap and safe halogenating reagents under
Pd‐Catalyzed
<i>N</i>
‐Arylations of 3‐Aryl‐1‐tosyl‐1
<i>H</i>
‐pyrazol‐5‐amines with Arylbromides and the Migration of Ts Group
作者:Jing He、Zhen Yang、Weiwei Li、Yueting Wei、Bin Dai、Jixing Zhao、Ping Liu
DOI:10.1002/cctc.202100193
日期:2021.6.8
AbstractAn efficient palladium‐catalyzed N‐arylations of 3‐aryl‐1‐tosyl‐1H‐pyrazol‐5‐amines with arylbromides is established. A series of diversified N‐arylated products are obtained in excellent yields with broad substrate scope. Importantly, the N‐arylated products undergo 1,4‐ and 1,6‐migration reactions of Ts group under the action of Cs2CO3, affording the N‐Ts‐substituted pyrroles as major products (1,6‐migration). Similar results can also be directly obtained by palladium‐catalyzed reactions of 3‐aryl‐1‐tosyl‐1H‐pyrazol‐5‐amines with arylbromides in the presence of Cs2CO3 as a base. Mechanistic studies reveal that the Ts‐migration is achieved through an intermolecular pathway.