Categories: Synthesis of N-Heterocycles >
Synthesis of dihydropyridines
Treatment of 6-alkoxy-1,4,5,6-tetrahydropyridines with neutral alumina (activity grade I) suspended in refluxing acetonitrile, afforded 1,4-dihydropyridines in excellent yields. This method allowed an efficient synthesis of 5,6-unsubstituted dihydropyridines, which are difficult to prepare by traditional methods, from acyclic and readily available precursors.
S. Maiti, J. C. Menéndez, Synlett, 2009, 2249-2252.
Metal perchlorates act as Lewis acid catalysts for the synthesis of 1,2,3,4-tetrasubstituted 1,4-dihydropyridines from enamino or carbonylic derivatives in moderate yields.
G. Bartoli, K. Babiuch, M. Bosco, A. Carlone, P. Galzerano, P. Melchiorre, L. Sambri, Synlett, 2007, 2897-2901.
HCl, generated in situ from 2,4,6-trichloro[1,3,5]triazine (TCT, cyanuric chloride), catalyzed a solvent free Hantzsch reaction at room temperature with enhanced reaction rates. The reaction conditions allow facile preparation of glycoconjugates of dihydropyridines under mild reaction conditions in high yields.
G. V. M. Sharma, K. L. Reddy, P. S. Lakshmi, P. R. Krishna, Synthesis, 2006, 55-58.
Covalently Anchored Sulfonic Acid on Silica Gel as an Efficient and Reusable Heterogeneous Catalyst for the One-Pot Synthesis of Hantzsch 1,4-Dihydropyridines under Solvent-Free Conditions
R. Gupta, R. Gupta, S. Paul, A. Loupy, Synthesis, 2007, 2835-2838.
Manganese mediates a direct functionalization of Hantzsch esters with readily accessible alkyl iodides through an aromatization–dearomatization strategy to provide valuable 4-alkyl-1,4-dihydropyridines in good yields under visible-light irradiation at room temperature. The reacton displays high functional-group compatibility and is applicable for gram-scale synthesis and late-stage functionalization.
X.-G. Liu, C.-S. Dong, F. Li, B. Zhang, Org. Lett., 2021, 23, 4002-4007.
An aluminum chloride promoted Hantzsch reaction of a wide range of N-tosylhydrazones provides a series of 1,4-dihydropyridines (1,4-DHPs) in good yields.
H. Wang, M. Tang, Synthesis, 2017, 49, 4893-4898.
Hantzsch 1,4-dihydropyridine and polyhydroquinoline derivatives were synthesized in excellent yields in aqueous micelles. The reaction is catalyzed by PTSA and strongly accelerated by ultrasonic irradiation.
A. Kumar, R. A. Maurya, Synlett, 2008, 883-885.
Facile Yb(OTf)3 promoted one-pot synthesis of polyhydroquinoline derivatives through Hantzsch reaction
L.-M. Wang, J. Sheng, L. Zhang, J.-W. Han, Z.-Y. Fan, H. Tian, C.-T. Qian, Tetrahedron, 2005, 61, 1539-1543.