1. 1-Haloacylpiperazines
S Groszkowski, J Sienkiewicz, L Korzycka Pol J Pharmacol Pharm. 1975 Apr-Jun;27(2):183-6.
By direct acylation of piperazine with halogenocarboxylic acid chlorides in acid medium, the hydrochlorides of 1-haloacylpiperazines were obtained.
2. Metal-free and regiospecific synthesis of 3-arylindoles
Chuangchuang Xu, Wenlai Xie, Jiaxi Xu Org Biomol Chem. 2020 Apr 8;18(14):2661-2671. doi: 10.1039/d0ob00317d.
A convenient, metal-free, and organic acid-base promoted synthetic method to prepare 3-arylindoles from 3-aryloxirane-2-carbonitriles and arylhydrazine hydrochlorides has been developed. In the reaction, the organic acid catalyzes a tandem nucleophilic ring-opening reaction of aryloxiranecarbonitriles and arylhydrazine hydrochlorides and Fischer indolization. The organic base triethylamine plays a crucial role in the final elimination step in the Fischer indole synthesis, affording 3-arylindoles regiospecifically. The reaction features advantages of microwave acceleration, non-metal participation, short reaction time, organic acid-base co-catalysis, and broad substrate scope.
