Selectivity tunable divergent synthesis of 1,4- and 1,2-dihydropyridines via three-component reactions

Construction of 3,12-Diazatetracyclododecane-dienes through Unexpected Visible-Light-Induced Radical Cascade Cyclization

A novel visible-light-induced cascade radical cyclization reaction of 3-cyano-4-aryl-1,4-dihydropyridines for the construction of 3,12-diazatetracyclododecane-diene derivatives is reported for the first time. In the presence of 410 nm blue LED lamp as the light source and ethanol as the solvent, the reactions proceed smoothly to afford photocyclization products in good yields. The process is carried out through the breaking of original C═C double bonds and the formation of three new single bonds in one pot and proved to be able to tolerate different substituents.

Crystal structure of dimethyl 1,4,6,9-tetraphenylhexahydro-3H-2,7,3,5-(epimethanetriyliminomethanetriyl)cyclopenta[b]pyridine-3,7(2H)-dicarboxylate, C38H34N2O4

C38H34N2O4, triclinic, P 1 ‾ $P\overline{1}$ (no. 2), a = 11.1158(19) Å, b = 11.302(2) Å, c = 12.634(2) Å, α = 72.109(2)°, β = 77.410(2)°, γ = 82.648(3)°, V = 1362.4(5) Å3, Z = 2, R gt (F) = 0.0473, wR ref (F 2) = 0.1738, T = 296 K.

Crystal structure of diethyl 4,6-diphenyl-1,9-di-p-tolylhexahydro-3H-2,7,3,5-(epimethanetriyliminomethanetriyl)cyclopenta[b]pyridine-3,5(2H)-dicarboxylate, C42H42N2O4

C42H42N2O4, triclinic, P 1 ‾ $P\bar{1}$ (no. 2), a = 9.309(3) Å, b = 14.191(5) Å, c = 14.918(5) Å, α = 69.221(4)°, β = 82.384(5)°, γ = 72.805(4)°, V = 1759.3(10) Å3, Z = 2, R gt (F) = 0.0699, wR ref (F 2) = 0.1806, T = 296 K.

Recent developments in the synthesis of nitrogen-containing heterocycles from β-aminovinyl esters/ketones as CC-N donors

Nitrogen-containing heterocycles are ubiquitous fragments of numerous natural products, pharmaceuticals, designed bioactive drug candidates and agrochemicals. During the past few decades, these compounds have received considerable attention from the synthetic chemistry community, and great efforts have been focused on the development of concise and efficient methods for the synthesis of these heterocyclic skeletons. In this review, we summarize a diverse range of synthetic methods employing β-aminovinyl esters(ketones) as key CC-N-synthons to furnish useful bioactive heterocyclic frameworks, such as quinolines, pyridines, pyrazines, pyrroles, indoles, oxazoles, imidazoles, thiazoles, isothiazoles, pyrazoles, triazoles, and azepines, thus offering new opportunities and expanding the toolbox of synthetic chemistry reactions.

Crystal structure of ethyl 1-(4-fluorophenyl)-4-phenyl-1H-pyrrole-3-carboxylate, C19H16FNO2

C19H16FNO2, monoclinic, P21/c (no. 14), a = 10.805(7) Å, b = 20.984(13) Å, c = 7.034(4) Å, β = 93.386(13)°, V = 1592.0(17), Z = 4, R gt (F) = 0.0561, wR ref (F 2) = 0.1336, T = 296 K.

Studies on chemoselective synthesis of 1,4- and 1,2-dihydropyridine derivatives by a Hantzsch-like reaction: a combined experimental and DFT study

In the experimental process of preparing diethyl 3,5-dicarboxylate-1,4-dihydropyridine (1,4-DHP) by a Hantzsch-like reaction, it was found that a by-product named diethyl 3,5-dicarboxylate-1,2-dihydropyridine (1,2-DHP) was produced in the reaction. To discuss this phenomenon, the effects of the reaction conditions on the yield ratio of 1,4-DHP and 1,2-DHP were studied by using aromatic amines, aromatic aldehydes and ethyl propiolate as raw materials. The mechanisms for the formation of 1,4-DHP and 1,2-DHP were proposed based on the isolated intermediate named diethyl 4-((phenylamino)methylene)pent-2-enedioate generated by the Michael addition of aniline and ethyl propiolate. The transition state structures were optimized and the reaction energy barriers of intermediates in the speculated mechanisms were calculated by DFT calculations at the M062X/def2TZVP//B3LYP-D3/def-SVP level. It was found that the reaction energy barriers and dominant configurations of intermediates IM2 and IM3' are the determinants for the chemoselectivity. Together, these results demonstrate a high chemoselectivity in the synthesis of 1,4-DHPs and 1,2-DHPs by a Hantzsch-like reaction and that 1,4-DHPs and 1,2-DHPs can be easily obtained under different conditions.

Metal-free multicomponent reactions: a benign access to monocyclic six-membered N-heterocycles

The advent of multicomponent reactions in the synthesis of heterocycles and their ever burgeoning applications in drug development, materials chemistry, and catalysis, have attracted a great deal of current scientific interest. In particular, the metal-free multicomponent synthesis of six membered N-heterocycles has undergone intensive research over the last two decades offering an environmentally benevolent means contrary to traditional metal catalysed reactions. To the best of our knowledge, there exists no exclusive review on the metal-free multicomponent synthesis of six membered N-heterocyles, and hence the present report highlights the progress on metal-free multicomponent reactions with their advantages and mechanistic insights to access monocyclic six-membered N-heterocycles including pyridine, pyrimidine, pyrazine, triazine and their hydrogenated derivatives. The literature is covered since 2000, and the contents offer not only striking methods for divergent synthesis of six-membered N-heterocycles but also put forward some new insights into the exploration of metal-free multicomponent chemistry.

Crystal structure of diethyl 3,9-bis(4-fluorophenyl)-6,12-diphenyl-3,9-diazapentacyclo[6.4.0.02,7.04,11]dodecane-1,5-dicarboxylate, C40H36F2N2O4

C40H36F2N2O4, monoclinic, P21/c (no. 14), a = 8.0755(7) Å, b = 19.7663(19) Å, c = 10.1987(9) Å, β = 95.940(2)°, V = 1619.2(3) Å3, Z = 4, R gt(F) = 0.0465, wR ref(F 2) = 0.1188, T = 296 K.

Crystal structure of diethyl 6,12-bis(4-fluorophenyl)-2,10-dimethoxy-3,9-diphenyl-3,9-diazatetracyclo[6.4.0.02,7.04,11]dodecane-1,5-dicarboxylate, C42H42F2N2O6

C42H42F2N2O6, monoclinic, P21/c (no. 14), a = 20.159(3) Å, b = 8.3357(10) Å, c = 21.372(3) Å, β = 103.130(3)°, V = 3497.4(8) Å3, Z = 4, R gt(F) = 0.0414, wR ref(F 2) = 0.1083, T = 113(2) K.

Substituent-controlled chemoselective synthesis of multi-substituted pyridones via a one-pot three-component cascade reaction

A substituent-controlled chemoselective cycloaddition reaction which afforded a variety of 2-pyridones and 4-pyridones in good to excellent yields, respectively, has been developed.

Divergent synthesis of dual 1,4-dihydropyridines with different substituted patterns from enaminones and aldehydes through domino reactions

A concise and efficient protocol for the regioselective synthesis of dual 1,4-dihydropyridines with several substituted patterns has been developed from a cascade cyclization of enaminones and aldehydes in different media (EtOH/CH3CN). The one-pot cascade reaction involves at least five reactive sites and generates multiple C-C and C-N bonds. The established protocol explores the chemistry of enaminones by employing their three reactive sites. The method has several advantages including mild conditions, operational simplicity, and high bond-forming efficiency. It may offer promise in a variety of biochemical applications.

Redox neutral [4+2] benzannulation of dienals and tertiary enaminones for benzaldehyde synthesis

The [4+2] benzannulation reactions between tertiary enaminones and dienals have been developed for the synthesis of polyfunctionalized benzaldehydes, providing a new access to benzaldehydes alongside the classical formylation strategy.

Regioselective three-component synthesis of 2,3-disubstituted quinolines via the enaminone modified Povarov reaction

The enaminone modified three-component Povarov reactions enable the regioselective synthesis of 2,3-disubstituted quinolines.

Metal-Free Synthesis of Fully Substituted Pyridines via Ring Construction Based on the Domino Reactions of Enaminones and Aldehydes

An unprecedented domino reaction involving primary enaminones/enaminoesters and aldehydes has been developed for the synthesis of fully substituted pyridines. The construction of the products has been accomplished via the cascade generation of two C-C and one C-N bond by simply using TfOH as a promoter.

Regioselective three-component reactions of enaminones, 2-aminopyridines and enals for the synthesis of 1,2-dihydropyridines

A novel regioselective, metal-free and broadly applicable three-component approach for the synthesis of 1,2-dihydropyridines has been established.

Copper-catalyzed three-component reactions of phenols, acyl chlorides and Wittig reagents for the synthesis of β-aryloxyl acrylates

A new protocol towards the diversity-oriented synthesis of β-aryloxyl acrylates has been developed using simple reactants and catalyst.

Metal-free synthesis of cyano acrylates via cyanuric chloride-mediated three-component reactions involving a cascade consists of Knoevenagel condensation/cyano hydration/esterification

The synthesis of cyano acrylates has been achieved via an organocatalytic domino Knoevenagel reaction, hydration and esterification under metal-free conditions without using any additional solvent.