Pd/C-catalyzed selective reduction of aromatic azides with Hantzsch 1,4-dihydropyridine

The reagent combination of Hantzsch 1,4-dihydropyridine and Pd/C was found to be an efficient reducing system for the selective reduction of aromatic azides.

Oxidative aromatization of Hantzsch 1,4-dihydropyridines by aqueous hydrogen peroxide-acetic acid

A simple method for the oxidative aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridines is achieved by using hydrogen peroxide as green oxidant and acetic acid as catalyst in aqueous solution.

ZrCl_4/Hantzsch 1,4-dihydropyridine as a new and efficient reagent combination for the direct reductive amination of aldehydes and ketones with weakly basic amines

ZrCl4/Hantzsch 1,4-dihydropyridine is a mild and highly efficient reagent combination for the direct reductive amination. Weakly basic amines such as anilines substituted by electron-withdrawing group and heteroaromatic amines can be reductively alkylated with electron rich aldehydes and ketones under mild conditions to form the secondary amines in excellent yields.

二茂铁基1,4-Dihydropyridine类似物的合成

A series of ferrocenyl 1,4 dihydropyridines were synthesized with high yields by a one pot cyclocondensation of formylferrocene,β ketoester and urea(or methyl 3 aminocrotonate) on the surface of SiO 2 under microwave irradiation without solvent.All products were characterized by EA,IR, and 1 HNMR.

Multicomponent Reaction in Ionic Liquid: A Novel and Green Synthesis of 1, 4-Dihydropyridine Derivatives

An efficient and green method for the synthesis of 1, 4-dihydropyridine derivatives mediated in an ionic liquid, [bmim][BF4], through a four-component condensation process of aldehydes, 1, 3-dione, Meldrum＇s acid and ammonium acetate is disclosed in this paper.

An Improved and Efficient Preparation of the Chiral NAD(P)H Model (S_s)-1-Benzy1-3-(p-tolylsulfinyl)-1,4-dihydropyridine

An improved procedure for the preparation of China, BAD(P)H model. (S_s)- 1 -benzyl-3- (p-tolylsulfinyl)-1.4-dihydropyridine with satisfactary chemical yield and excellent enantiopurity is reported.

n-Butyltriphenylphosphonium peroxodisulfate:A cheap and efficient reagent for the aromatization of Hantzsch 1,4-dihydropyridines

Different 4-substituted 1,4-dihydropyridines have been oxidized to pyridine derivatives by n-butyltriphenyl phosphonium peroxodisulfate in acetonitrile solution at reflux condition. Formation of two kinds of products has been observed depending on the type of 4-substituent.

Photooxidation of Hantzsch 1,4-dihydropyridines by molecular oxygen

Photooxidation of Hantzsch 1,4-dihydropyridines (1,4-DHP,1a-1d) by direct irradiation (λ > 300 nm) under an oxygen atmosphere has been carefully examined in this work. Spectroscopic and electrochemical studies demonstrate that photoinduced singlet electron transfer from 1,4-DHP to molecular oxygen occurs. The generated superoxide radical anion (O2-·) is responsible for this typical photochemical oxidation.

Visible-Light-Mediated Photocatalyst-Free Hydroacylation of Azodicarboxylic Acid Derivatives with 4-Acyl-1,4-dihydropyridines

A visible-light-enabled,photocatalyst-free hydroacylation reaction of azodicarboxylic acid derivatives was described.This radical conjugate addition(RCA)protocol relied on the dual role of 4-acyl-1,4-dihydropyridine(acyl-DHP)reagents that besides being as radical reservoirs,they also enabled the conversion of radical adducts to anion intermediates via reduction.Under“catalyst-oxidant-additive free”conditions,a wide range of structurally different acyl hydrazide products were readily obtained in 56%—99%yields.The utility of this transformation was further demonstrated by the scale-up synthesis and downstream derivatization.

LiBr as an Efficient Catalyst for One-pot Synthesis of Hantzsch 1,4-Dihydropyridines under Mild Conditions

A simple, inexpensive and efficient one-pot synthesis of 1,4-dihydropyridines has been accomplished via lithium bromide-catalyzed Hantzsch three-component condensation reaction of an aldehyde, α,β-ketoester and ammonium acetate in acetonitrile at room temperature in good to excellent yields. The present protocol is applicable to wide range of substrates including aliphatic, aromatic and heterocyclic aldehydes affording 1,4-dihydropyridines.

Synthesis of Some New 1,4-Dihydropyridine Derivatives through a Facile One-pot Hantzsch Condensation Catalyzed by Triethylamine

A facile and efficient synthesis of new 1,4-dihydropyridine derivatives was reported via Hantzsch three-com- ponent condensation reaction of aldehydes or formylphenylboronic acids, ethyl acetoacetate, and ammonium acetate in the presence of a catalytic amount of triethylamine under solvent-free conditions. The method described here of- fers several advantages including high yields, short reaction times, and simple work-up procedure.

An Efficient, Three-component One-pot Preparation of 1,4-Dihydropyridines Containing Novel Substituted Pyrazole under Sulfamic Acid Catalysis

An efficient approach to 1,4-dihydropyridines containing novel substituted pyrazole is achieved via threecomponent reaction of pyrazolyl aldehyde, β-ketoester, and ammonium acetate in one-pot under sulfamic acid catalysis.

An efficient and solvent-free one-pot synthesis of 1,4-dihydropyridines under microwave irradiation

An efficient synthesis of 1,4-dihydropyridines using lanthanum oxide as a catalyst from aldehydes,β-ketoester and ammonium acetate without solvent under the irradiation of microwave is described.Compared with the classical Hantzsch reaction,this new method has the advantage of good yield（90-98%） and short reaction time（40-80 s）.

Silica-supported Perchloric Acid Catalyzed One-pot Synthesis of 1,4-Dihydropyridines

An environmentally friendly and highly efficient procedure for the preparation of 1,4-dihydropyridines by the reaction between a,β-unsaturated aldehydes, aromatic amines and β-keto esters in the presence of silica supported perchloric acid is described.

Application of Enzymatic Promiscuity in Pharmaceutical Synthesis:Papain-catalyzed One-pot Synthesis of 1,4-Dihydropyridine Calcium Channel Antagonists and Derivatives

A new method for the synthesis of 1,4-dihydropyridine(1,4-DHP)calcium channel antagonists felodipme, nitrendipine and their derivatives via papain-catalyzed three-component reactions of aldehyde,methyl acetoacetate and ethyl 3-aminocrotonate was developed.Operational simplicity,mild reaction conditions and eco-friendliness are the key features of this protocol.

An efficient three-component domino synthesis of difluoromethyl-containing 1,4-dihydropyridines under solvent and catalyst free conditions

The difluoromethyl-containing Hantzsch 1,4-dihydropyridines were synthesized in good yields by a one-pot cyclocondensation of ethyl difluoroacetoacetate (EDFAA),a variety of aromatic aldehydes and ammonium acetate under solvent and catalyst free conditions.The comparison of reaction conditions and products was made among the different 1,3-carbonyl substrates (ethyl acetoacetate,ethyl difluoroacetoacetate and ethyl trifluoroacetoacetate) for the Hantzsch reaction.

One-pot Multicomponent Synthesis of Highly Functionalized 1,4-Dihydropyridines Using Porcine Pancreatic Lipase

A series of highly timctionalized 1,4-dihydropyridines was synthesized via one-pot multicomponent reactions of aromatic aldehyde,malononitrile and N-methyl-1-(methylthio)-2-nitroethenamine using Porcine pancreatic lipase(PPL)as catalyst in DMSO.This protocol is featured by mild reaction conditions,simple operation and environmental acceptability.

Multicomponent Reactions for Diverse Synthesis of N-Substituted and NH 1,4-Dihydropyridines

The multicomponent reactions of aldehydes,electron deficient alkynes and amines have been successfully per-formed to yield a number of symmetrical 2,6-unsubstituted 1,4-dihydropyridines(1,4-DHPs).This method has been found generally applicable for the synthesis of both N-substituted and N-unsubstituted 1,4-DHPs by employing secondary amine to activate the alkyne component via enaminoester intermediates.The present method runs through an enamine type activation,which is different from the known approach employing AcOH as solvent.

Design and Synthesis of 1,4-Dihydropyridine and Cinnamic Acid Esters and Their Antioxidant Properties

In this study, cinnamic acid derivatives with pyridine ring were synthesized via Hantzsch reaction in order to expand conjugation system and their antioxidant abilities were tested. According to the evaluation results of their antioxidant properties, compounds 2 and 3 have similar antioxidant activity to prevent DNA from ＊OH- and Cu2＋/GSH induced oxidation, demonstrating that 1,4-dihydropyridine and pyridine nucleus exhibit good resistance to oxidation while the substituents have little effect. In the meantime, the AAPH-induced oxidative DNA damage [AAPH=2,2＇-azobis（2-methylpropionamidine）dihydrochloride] and trapping ABTS＋＊ test show that N--H bond and large conjugation systems are the pivotal parts to improve the activities of antioxidant.

Construction of 3,9-diazatetraasteranes and 3,9-diazatetracyclododecanes by photocycloaddition reaction of 1,4-dihydropyridines:Experimental and theoretical investigation

A photocycloaddition reaction of ethyl 1,4-diaryl-1,4-dihydropyridine-3-carboxylate for the construction of 3,9-diazatetraasteranes(Pr)and 3,9-diazatetracyclododecanes(P2)is reported for the first time.The types of reaction product clearly differ with solvent,regardless of the irradiation wavelength.The difference in Pi and P2 lies in the second step of the intramolecular[2+2]photocyclization.In order to further investigate this phenomenon and gain a deeper understanding of the photochemical behavior of 1,4-dihydropyridines,DFT and TDDFT theoretical calculations are performed.The results provide a good explanation for the formation of 3,9-diazatetraasteranes and 3,9-diazatetracyclododecanes.