Synthesis 2022; 54(13): 3114-3124
DOI: 10.1055/s-0041-1737395
paper

Facile One-Pot Preparation of 5-Substituted 4-Iodo-1-tosylpyrazoles from N-Propargyl-N′-tosylhydrazines through Iodocyclization

Aya Saito
,
Kazuhiro Yoshida
,
Hideo Togo
This work was supported by JSPS KAKENHI Grant Number JP18K05118 in Japan.


Abstract

Treatment of N-propargyl-N′-tosylhydrazines with molecular iodine (I2) in the presence of NaHCO3 under warming conditions gave efficiently the corresponding 5-substituted 4-iodo-1-tosylpyrazoles in good to moderate yields. In addition, the same reaction in the presence of acetic acid generated the corresponding 5-aryl-4-iodopyrazoles in moderate yields. The reactions are simple and efficient transition-metal-free methods for the preparation of 5-substituted 4-iodo­pyrazole unit.

Supporting Information



Publication History

Received: 18 January 2022

Accepted after revision: 15 February 2022

Article published online:
28 March 2022

© 2022. Thieme. All rights reserved

Georg Thieme Verlag KG
Rüdigerstraße 14, 70469 Stuttgart, Germany