A novel transformation of beta-1,2,3-thiadiazol-5-yl enamines into thieno[2,3-d]pyridazines

作者：Rozin Yuri; Zhidovinov Sergey; Beryozkina Tetyana^*; Shafran Yuri; Lubec Gert; Eltsov Oleg; Slepukhin Pavel; Knippschild Uwe; Bischof Joachim; Dehaen Wim; Bakulev Vasiliy

来源：Tetrahedron Letters, 2015, 56(12): 1545-1547.

DOI：10.1016/j.tetlet.2015.02.013

• Enamines
• Thieno[2,3-d]pyridazines
• Thiadiazoles
• Transformation
• Rearrangement

Reactions of beta-1,2,3-thiadiazol-5-yl enamines with acetyl chloride in 1,4-dioxane lead to the formation of either dienamines or novel thieno[2,3-d]pyridazines depending on the time and reaction temperature. Conditions were found for the selective synthesis of thieno[2,3-d]pyridazines. A plausible mechanism involves formation of C-S and C-C bonds and a novel ring rearrangement of 5-vinyl-1,2,3-thiadiazoles into pyridazine-4-thiolates. A series of new diamides of 2-(4-carboxy-1,2,3-thiadiazol-5-yl)thieno[2,3-d]pyridazine-7-carboxylic acid is prepared by reaction of the methyl ester with primary and secondary amines.

• 出版日期2015-3-18