Categories: Synthesis of N-Heterocycles >
Synthesis of 1,2,4-triazines
A redox-efficient cyclodehydration of β-keto-N-acylsulfonamides with hydrazine salts provides 3,6-disubstituted-1,2,4-triazines. The mild reaction conditions tolerate a variety of sensitive functionalities. In addition, two approaches for synthesizing the requisite β-keto-N-acylsulfonamides are presented, which allow for the late stage incorporation of either the C3 or C6 substituent in a flexible manner.
M. S. Dowling, W. Jiao, J. Hou, Y. Jiang, S. Gong, J. Org. Chem., 2018, 83, 4229-4238.
An unexpected rhodium-catalyzed O-H insertion/rearrangement of N-acylhydrazones with N-sulfonyl-1,2,3-triazoles provides common intermediates for the synthesis of 1,2,4-triazines with different substitution patterns. Subsequent intramolecular cyclization reactions under mild conditions yield 3,6-disubstituted- and 3,5,6-trisubstituted-1,2,4-triazines depending on the conditions.
J. Meng, M. Wen, S. Zhang, P. Pan, X. Yu, W.-P. Deng, J. Org. Chem., 2017, 82, 1676-1687.