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Updated: Aug 19, 2026

Chemoselective Preparation of 1-Iodoalkynes, 1,2-Diiodoalkenes, and 1,1,2-Triiodoalkenes Based on the Oxidative Iodination of Terminal Alkynes
Published on: September 12, 2018
Iodine/TBAB-promoted oxidative cyclization: an efficient approach to thiadiazoles
Rakshanda Singhal1, Manish K Mehra2, Babita Malik1
1Department of Chemistry, School of Physical and Biological Sciences, Manipal University Jaipur VPO-Dehmi-Kalan, Off Jaipur-Ajmer Express Way Jaipur Rajasthan 303007 India meenakshi.pilania@jaipur.manipal.edu meenakshi.pilania1987@gmail.com.
None:
A rapid and efficient method for synthesizing 2-amino-1,3,4-thiadiazoles and 1,2,3-thiadiazoles via the oxidative cyclization of N-tosylhydrazones obtained from aromatic aldehydes and acetophenones has been developed. The reaction uses potassium thiocyanate or elemental sulphur as its sulphur source, with tetrabutylammonium bromide (TBAB) as a promoter in molecular iodine and a DMSO solvent system. This approach produces moderate to high yields across a wide range of substrates and proceeds smoothly within 5-15 minutes. Avoiding the use of column chromatography improves the environmental sustainability, scalability, and practicality of the synthetic protocol. This TBAB-assisted approach delivers more effectiveness and more applicability than traditional catalyst-free methods, providing a useful framework for thiadiazole synthesis that is highly useful for heterocyclic and medicinal chemistry.
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