Base‐Promoted Synthesis of 2,4,6‐Triarylpyridines from Enaminones and Chalcones

Abstract

Ap rotocol for the synthesis of 2,4,6-trisubstituted pyridinesf rom N-unsubstituted enaminones and chalcones via base-promoted tandem Michael/cyclization reaction has been developed.T his methodp rovides an efficient, convenient route to 2,4,6-trisubstituted pyridines with ag ood functional group tolerance under mild conditions in the absence of transition metal.

Cu(II)‐Catalyzed Synthesis of 2,3,6‐Trisubstituted Pyridines from Saturated Ketone and Alkynones/1,3‐Dicarbonyl Compounds

“…[11] Then, some other synthetic methods of polysubstituted pyridines were also reported, Cui's group achieved synthesis of 2,4,6-triarylpyridines from enaminones and chalcones under the promotion of base(Scheme 2, (c)). [12] Inspired by these precedents, we conceived that the conformation of electron-eficient enamines and polysubstituted pyridines could occur in a one-pot manner. Herein we report a novel strategy to synthesize 2,3,6trisubstituted pyridines from easily accessible alkynones or 1,3dicarbonyl compounds, inactivated saturated ketones and ammonium salt under Cu(II)-catalyzed condition.…”

Cationic organotin cluster [t‐Bu2Sn(OH)(H2O)]22+2OTf−‐catalyzed one‐pot three‐component syntheses of 5‐substituted 1H‐tetrazoles and 2,4,6‐triarylpyridines in water

“…[15] Consequently, various synthetic methods have been developed for the synthesis of 2,4,6-triarylpyridines, [16] such as the coupling of aryl aldehydes with aromatic keto-oxime acetates, [17] oxidative cleavage of C&bond;N bonds of benzyl amines with aromatic ketones [18] and the reactions of aromatic ketones with benzylamines, [19] acetophenoneoximes with aldehydes [20] or epoxy styrenes, [21] benzyl halides with acetophenones, [22] and chalcones with enaminones. [23] The cyclocondensation reaction of acetophenones, benzaldehydes and ammonium acetate is known as one of the most conventional pathways for the synthesis of 2,4,6-triarylpyridines in the presence of various catalysts such as PEG 1000 -DAIL, [24] ionic liquid, [25] PFPAT, [26] MIL-101-SO 3 H, [27] DPTA, [28] ZrOCl 2, [29] TiO 2 -SO 3 H, [30] TCT, [31] Fe 3 O 4 @TiO 2 @O 2 PO 2 (CH 2 ) 2 NHSO 3 H, [32] HClO 4 /SiO 2 [33] or without catalyst. [34] However, many of the established methods are subject to certain disadvantages including use of large amounts of catalyst and long reaction times.…”

“…Substituted 2,4,6‐triarylpyridines have been extensively exploited as chemosensors, as photosensitizers and as intermediates in the synthesis of therapeutic drugs, insecticides, herbicides and surfactants . Consequently, various synthetic methods have been developed for the synthesis of 2,4,6‐triarylpyridines, such as the coupling of aryl aldehydes with aromatic keto‐oxime acetates, oxidative cleavage of C&bond;N bonds of benzyl amines with aromatic ketones and the reactions of aromatic ketones with benzylamines, acetophenoneoximes with aldehydes or epoxy styrenes, benzyl halides with acetophenones, and chalcones with enaminones . The cyclocondensation reaction of acetophenones, benzaldehydes and ammonium acetate is known as one of the most conventional pathways for the synthesis of 2,4,6‐triarylpyridines in the presence of various catalysts such as PEG 1000 ‐DAIL, ionic liquid, PFPAT, MIL‐101‐SO 3 H, DPTA, ZrOCl 2, TiO 2 ‐SO 3 H, TCT, Fe 3 O 4 @TiO 2 @O 2 PO 2 (CH 2 ) 2 NHSO 3 H, HClO 4 /SiO 2 or without catalyst .…”

Unusual Reactivity of 4-Vinyl Isoxazoles in the Copper-Mediated Synthesis of Pyridines, Employing DMSO as a One-Carbon Surrogate

“…Pyridines represent an important class of heterocyclic scaffolds in biologically relevant molecules and serve as versatile building blocks in the synthesis of many natural products, bioactive compounds, and pharmaceutical agents. − Pyridines and their derivatives are also useful ligands in various metal-catalyzed organic transformations. , Traditional approaches to their synthesis involve condensation and aromatization of various carbonyl compounds or α,β-unsaturated carbonyl compounds with ammonia or its derivatives. − In recent times, metal-catalyzed cyclization reactions have proven to be efficient routes for the synthesis of substituted pyridines and various efficient approaches have been successfully developed by several research groups to produce nicotinate skeletons by employing electron-deficient β-enamino esters and their condensation with 1,3-dicarbonyl compounds (Scheme ). − Despite these advances, the development of newer methods for the efficient construction of pyridines continues to attract considerable attention from chemists.…”