Categories: Synthesis of N-Heterocycles > benzo-fused N-Heterocycles >
Synthesis of 1,2,4-triazolo[4,3-a]pyridines
Recent Literature
An environmentally benign synthesis of various 3,4,5-trisubstituted
1,2,4-triazoles and N-fused 1,2,4-triazoles via ceric ammonium nitrate
catalyzed oxidative cyclization of amidrazones and aldehydes using polyethylene
glycol as recyclable reaction medium is economic and potentially viable for
commercial applications.
M. Nakka, R. Tadikonda, S. Rayavarapu, P. Sarakula, S. Vidavalur, Synthesis, 2015, 47,
517-525.
An operationally efficient CDI mediated tandem coupling and cyclization reaction
provides [1,2,4]triazolo[4,3-a]pyridines. The methodology is suitable for
batch mode as well as continuous process.
K. D. Baucom, S. C. Jones, S. W. Roberts, Org. Lett., 2016, 18,
560-563.
An efficient and convenient synthesis of [1,2,4]triazolo[4,3-a]pyridines
involves a palladium-catalyzed addition of hydrazides to 2-chloropyridine, which
occurs chemoselectively at the terminal nitrogen atom of the hydrazide, followed
by dehydration in acetic acid under microwave irradiation.
A. Reichelt, J. R. Falsey, R. M. Rzasa, O. R. Thiel, M. M. Achmatowicz, R. D.
Larsen, D. Zhang, Org. Lett., 2010,
12, 792-795.
An electrochemically induced desulfurative cyclization of
2-hydrazinopyridines with isothiocyanates provides a wide range of
3-amino-[1,2,4]-triazolo pyridines and related heterocycles under simple
conditions without transition metals or external oxidants. This strategy offers
broad substrate scope, good functional group compatibility, and gram-scale
synthesis.
Y. Hu, L. Chen, C. Zou, J. He, L. Feng, J.-Q. Wu, W.-H. Chen, J. Hu, Org. Lett.,
2022, 24, 5137-5142.
I2-mediated oxidative C-N and N-S bond formations in water enable a
metal-free, environmentally benign and convenient strategy for the synthesis of
4,5-disubstituted/N-fused 3-amino-1,2,4-triazoles and 3-substituted
5-amino-1,2,4-thiadiazoles from isothiocyanates. The scalable protocols
exhibited excellent substrate tolerance.
N. Jatangi, N. Tumula, R. K. Palakodety, M. Nakka, J. Org. Chem., 2018, 83,
5715-5723.