Micellaktivierte Reaktionen I. Micellaktivierte Iodierung und partielle Dehalogenierung von Pyrazolen und 1,2,4‐Triazolen

Micelle Activated Reactions I. Micelle Activated Iodination and Partial Dehalogenation of Pyrazoles and 1,2,4‐Triazoles A method is described to iodinate pyrazole, substituted pyrazoles or 1,2,4‐triazole with iodine or iodine chloride in aqueous alkaline in the presence of an anionic surfactant. 4‐Iodo‐( 2a ), 4‐iodo‐3(5)‐methyl‐ ( 2b ), 3(5),4‐diiodo‐ ( 3a ), 3(5),4‐diiodo‐5(3)‐methyl‐ ( 3b ), and 3,4,5‐triiodo‐pyrazole ( 3d ) as soon as 4‐iodo‐pyrazole‐3(5)‐carboxylic acid ( 2c ), and 3(5)‐iodo‐1,2,4‐triazole ( 5 ) were prepared. Anhydrous hydrogen fluoride or triethylamine trishydrofluoride were found to be a suitable agent to effect a regioselective partial dehalogenation of 3b, 3d and 3,5‐dibromo‐1,2,4‐triazole ( 7 ). We prepared 3(5)‐iodo‐5(3)‐methyl‐pyrazole ( 6b ), 3,5‐diiodo‐pyrazole ( 6d ) and 3(5)‐bromo‐1,2,4‐triazole ( 8 ) on this way.