4926-16-3Relevant articles and documents
Metal free [4+1] and [5+1] annulation reactions to prepare heterocycles using DMF and its derivatives as one-carbon source
Liu, Lingfeng,Qiao, Chunhua,Shen, Bei,Xu, Yiwen
, (2020/04/01)
1,2,4-Triazolo[3,4-a]pyridines and related heterocycles and substituted triazines were commonly discovered scaffolds in a variety of pharmaceutical and agrochemical agents. Herein, we report a highly efficient and practical method using DMF and its derivative for the [4+1] and [5+1] annulation reactions to prepare these heterocycles. This metal free reaction takes advantages of shelf stable DMF as solvent and carbon donor, imidazole chloride as a catalyst, the mild reaction condition tolerates a broad substrate range and substitutes. The prepared 3-unsubstituted 1,2,4-triazolo[3,4-a]pyridine and derivatives allow further introduction of a variety of functional group1 at 3-position.
A mild synthesis of [1,2,4]triazolo[4,3-a]pyridines
Schmidt, Michael A.,Qian, Xinhua
supporting information, p. 5721 - 5726 (2013/09/24)
The reaction between 2-hydrazinopyridines and ethyl imidates was examined as a one-pot method for rapidly preparing [1,2,4]triazolo[4,3-a]pyridines. A diverse set of 2-hydrazinopyridines were cyclized with a variety of alkyl- and aryl-substituted ethyl imidates in good yields. The reaction proceeds optimally under mild conditions (50-70 C) using 1.5 equiv of acetic acid. The electronic and steric properties of the hydrazine and imidate strongly impact the rate of the reaction. When highly electron deficient 2-hydrazinopyridines were used, the products rearranged to [1,2,4]triazolo[1,5-a]pyridines.
