Categories: Synthesis of N-Heterocycles > benzo-fused N-Heterocycles >
Synthesis of imidazo[1,5-a]pyridines
Recent Literature
Copper(I) catalysis enables a direct transannulation of N-heteroaryl aldehydes
or ketones with alkylamines via Csp3-H amination in the
presence of oxygen as the sole oxidant. This transformation provides
a rapid and concise access to multifunctional imidazo[1,5-a]pyridines.
M. Li, Y. Xie, Y. Ye, Y. Zou, H. Jiang, W. Zeng, Org. Lett.,
2014,
16, 6232-6235.
A copper/iodine cocatalyzed decarboxylative cyclization of α-amino acids with
either 2-benzoylpyridines or 2-benzoylquinolines provides 1,3-disubstituted
imidazo[1,5-a]pyridines and 1,3-disubstituted imidazo[1,5-a]quinolines
in excellent yields.
H. Wang, W. Xu, L. Xin, W. Liu, Z. Wang, K. Xu, J. Org. Chem.,
2016,
81, 3681-3687.
A copper(II)-catalyzed tandem reaction between pyridine ketone and benzylamine
proceeded via an efficient condensation-amination-oxidative dehydrogenation
process, affording 1,3-diarylated imidazo[1,5-a]pyridines in excellent
yields using clean O2 as an oxidant.
H. Wang, W. Xu, Z. Wang, L. Yu, K. Xu, J. Org. Chem.,
2015,
80, 1856-1865.
An efficient three-component coupling reaction of substituted picolinaldehydes,
amines, and formaldehyde produces imidazo[1,5-a]pyridinium ions in high
yields under mild conditions, allowing the incorporation of diverse
functionality and chiral substituents. Higher order condensations are also
described that provide access to multidentate NHC ligands useful for a variety
of applications.
J. T. Hutt, Z. D. Aron, Org. Lett., 2011,
13, 5256-5259.
An iron-catalyzed efficient C-H amination for the construction of
imidazole-fused-ring systems can be conducted in anisole as green solvent with
water as the only byproduct. The reaction provides Imidazo[1,5-a]pyridines,
imidazo[5,1-b]oxazoles, imidazo[5,1-b]thiazoles, imidazo[1,5-a]pyrazines,
and imidazo[1,5-a]imidazoles.
J. Peng, S. Li, J. Huang, Q. Meng, L. Wang, W. Xin, W. Li, W. Zhou, L. Zhang, J. Org. Chem., 2023, 88,
16581-16588.
A denitrogenative transannulation of pyridotriazoles with nitriles using BF3·Et2O
as catalyst provides imidazo[1,5-a]pyridines. The combination of solvents
(dichlorobenzene-dichloroethane) plays a crucial role in achieving quantitative
yields of desired products under metal-free conditions.
A. Joshi, D. C. Mohan, S. Adimurthy, J. Org. Chem.,
2016, 81, 9461-9469.
A metal-free sequential dual oxidative amination of C(sp3)-H bonds
under ambient conditions affords imidazo[1,5-a]pyridines in very good yields.
The reaction involves two oxidative C-N couplings and one oxidative
dehydrogenation process with six hydrogen atoms removed.
Y. Yan, Y. Zhang, Z. Zha, Z. Wang, Org. Lett., 2013,
15, 2274-2277.
Heterocyclic benzylamines can be reacted with TFAA as trifluoromethylating
reagent to provide imidazo-fused N-heterocycles. Alternatively, a two-step
synthesis of trifluoromethylated imidazo-fused N-heterocyles from heterocyclic
benzyl (pseudo)halides using trifluoroacetamide as trifluoromethylating reagent
proceeds via alkylation followed by dehydrative cyclization.
G. Schäfer, M. Ahmetovic, S. Abele, Org. Lett.,
2017, 19, 6578-6581.