Cross‐Linked‐Polymer‐Supported N‐{2′‐[(Arylsulfonyl)amino][1,1′‐binaphthalen]‐2‐yl}prolinamide as Organocatalyst for the Direct Aldol Intermolecular Reaction under Solvent‐Free Conditions

A bottom‐up strategy was used for the synthesis of cross‐linked copolymers containing the organocatalyst N‐{(1R)‐2′‐{[(4‐ethylphenyl)sulfonyl]amino}[1,1′‐binaphthalen]‐2‐yl}‐D ‐prolinamide derived from 2 (Scheme 1). The polymer‐bound catalyst 5b containing 1% of divinylbenzene as cross‐linker showed higher catalyst activity in the aldol reaction between cyclohexanone and 4‐nitrobenzaldehyde than 5a and 5c . Remarkably, the reaction in the presence of 5b was carried out under solvent‐free, mild conditions, achieving up to 93% ee (Table 1). The polymer‐bound catalyst 5b was recovered by filtration and re‐used up to seven times without detrimental effects on the achieved diastereo‐ and enantioselectivities (Table 2). The catalytic procedure with polymer 5b was extended to the aldol reaction under solvent‐free conditions of other ketones, including functionalized ones, and different aromatic aldehydes (Table 3). In some cases, the addition of a small amount of H₂O was required to give the best results (up to 95% ee). Under these reaction conditions, the cross‐aldol reaction between aldehydes proceeded in moderate yield and diastereo‐ and enantioselectivity (Scheme 2).     

A Stereoselective Aldol Approach for the Total Syntheses of Two 6‐Alkylated 2H‐Pyran‐2‐ones

A simple and highly efficient stereoselective total synthesis of the 6‐alkylated pyranones (6R)‐6‐[(1E,4R,6R)‐4,6‐dihydroxy‐10‐phenyldec‐1‐en‐1‐yl]‐5,6‐dihydro‐2H‐pyran‐2‐one ( 1 ) and (6S)‐5,6‐dihydro‐6‐[(2R)‐2‐hydroxy‐6‐phenylhexyl]‐2H‐pyran‐2‐one ( 2 ) was developed using Crimmins' aldol reaction, SmI₂ reduction, Grubbs‐II‐catalyzed olefin cross‐metathesis, and Still's modified Horner? Wadsworth? Emmons reaction.     

One‐Pot synthesis of a novel compound N‐hydroxydecahydroacridine under microwave irradiation

A novel reaction to synthesis a series new N‐hydroxyldecahydroacridine derivatives by a one‐pot condensation of aldehyde, 1,3‐dicarbonyl compound and NH₂OH in glycol under microwave irradiation is described. N‐hydroxyldecahydroacridine was obtained in excellent yields (81–95%) within short reaction time (4–7 min)     

Formation of Dimers of Some 2‐Substituted Indan‐1‐one Derivatives during Base‐Mediated Cross‐Aldol Condensation

Unexpected dimers of some 2‐substituted indan‐1‐one derivatives were isolated during aldol condensation of indan‐1‐one with various aldehydes in the presence of KOH (see Scheme). Monomeric products, usually expected from aldol condensation, further underwent a base‐catalyzed nucleophilic addition reaction to their dimeric form in some cases. The structures of these dimers were characterized by using various spectral techniques and in one case, structural details were determined from a high‐resolution crystallographic analysis.     

Dinitrogen‐Molybdenum Complex Induces Dinitrogen Cleavage by One‐Electron Oxidation

Reported here is the N₂ cleavage of a one‐electron oxidation reaction using trans‐[Mo(depe)₂(N₂)₂] ( 1 ) (depe=Et₂PCH₂CH₂PEt₂), which is a classical molybdenum(0)‐dinitrogen complex supported by two bidentate phosphine ligands. The molybdenum(IV) terminal nitride complex [Mo(depe)₂N][BArf₄] ( 2 ) (BArf₄=B(3,5‐(CF₃)₂C₆H₃)₄) is synthesized by the one‐electron oxidation of 1 upon addition of a mild oxidant, [Cp₂Fe][BArf₄] (Cp=C₅H₅), and proceeds by N₂ cleavage from a Mo^II‐N=N‐Mo^II structure. In addition, the electrochemical oxidation reaction for 1 also cleaved the N₂ ligand to give 2 . The dimeric Mo complex with a bridging N₂ is detected by in situ resonance Raman and in situ UV‐vis spectroscopies during the electrochemical oxidation reaction for 1 . Density‐functional theory (DFT) calculations reveal that the unstable monomeric oxidized Mo^I species is converted into 2 via the dimeric structure involving a zigzag transition state.     

Proline‐Tetrazole‐Catalyzed Enantioselective N‐Nitroso Aldol Reaction of Aldehydes with In Situ Generated Nitrosocarbonyl Compounds

A highly enantioselective method (up to 98 % ee) for the preparation of β‐amino alcohols was achieved by using the readily available proline‐tetrazole as the catalyst for the N‐nitroso aldol reaction of aldehydes with in situ generated nitrosocarbonyl compounds. The key to success of this reaction is the use of MnO₂ as an oxidant and catechol as a Brønsted acid additive.     

One‐Pot Synthesis of 1,3,5‐Triarylpyrazoles

A series of novel 1,3,5‐triarylpyrazoles 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , 3m , 3n , 3o , 3p , 3q , 3r , 3s , 3t , 3u , 3v , 3w , 3x were synthesized from flavanones, arylhydrazines, and trimethyl phosphate in an one‐pot procedure. Facile reaction process, easy after‐reaction workshop, and good yields are the distinct characteristics of the developed protocol. The target compounds were characterized by element analysis, infrared ray (IR), ¹H NMR spectra, and electrospray ionization‐mass spectrometry. The structure of representative compound 3h (C₂₃H₂₀N₂O₃, M_r = 372.42) was further confirmed by X‐ray diffraction. It crystallizes in monoclinic, space group P 2₁/c, a = 8.9720(5), b = 24.5523(13), c = 8.9687(6) Å, α = 90.0000, β = 102.6417(17), γ = 90.0000°, V = 1927.76(20) ų, Z = 4, μ(MoKα) = 0.086, F(000) = 784, D_c = 1.283 g/cm³, the final R = 0.0349 and wR = 0.0844 for 1668 observed reflections (I > 2σ(I))     

Zinc(II)‐Catalyzed Intermolecular Hydrative Aldol Reactions of 2‐En‐1‐ynamides with Aldehydes and Water to form Branched Aldol Products Regio‐ and Stereoselectively

This work describes zinc(II)‐catalyzed hydrative aldol reactions of 2‐en‐1‐ynamides with aldehydes and water to afford branched aldol products regio‐ and stereoselectively. The anti and syn selectivity can be modulated by the sizes of sulfonamides to yield E‐ and Z‐configured zinc(II) dienolates selectively. This new reaction leads to enantiopure aldol products by using a cheap chiral sulfonamide. The mechanistic analysis reveals that the sulfonamide amides of the substrates can trap a released proton to generate dual acidic sites to activate a carbonyl allylation reaction.     

Highly Efficient One‐Pot Three‐Component Synthesis and Antimicrobial Activity of 2‐Amino‐4H‐chromene Derivatives

A remarkably efficient three‐component reaction to synthesize 2‐amino‐4H‐chromenes derivatives from malononitrile, various aromatic aldehydes, and orcinol was described at room temperature in CH₂Cl₂ in the presence of catalytic amount of triethylamine. In a facile one‐pot procedure, excellent yields of products were achieved in less than 1 h. Some of the synthesized 2‐amino‐4H‐chromenes derivatives demonstrated potent antibacterial activities against Gram‐positive bacteria including Staphylococcus aureus and Bacillus anthracis, indicated by disk method, minimum inhibitory concentration, and minimum bactericidal concentration approaches. However, none of the tested compounds expressed any antibacterial activities against Enterococcus faecalis and Gram‐negative bacteria.     

One‐Pot,Pseudo‐Five‐Component Synthesis of Bis[2‐(arylimino)‐1,3‐thiazolidin‐4‐ones]

Synthesis and characterization of bis[2‐(arylimino)‐1,3‐thiazolidin‐4‐ones] are described. The one‐pot, pseudo‐five‐component reaction of an aliphatic diamine, isothiocyanatobenzene, and dialkyl but‐2‐ynedioate at room temperature in anhydrous CH₂Cl₂ gives the title compound in relatively high yield. Under the same conditions, aromatic 1,2‐diamines yield 2‐(arylimino)‐N‐(enaminoaryl)‐1,3‐thiazolidin‐4‐ones in a pseudo‐four‐component reaction. Their structures were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of cyclization is proposed (Scheme 3).     

A Green Synthesis of 2‐Amino‐4‐(9H‐carbazole‐3‐yl)thiophene‐3‐carbonitriles by a Step‐wise and One‐pot Three‐component Gewald Reaction

An eco‐friendly method has been developed for the synthesis of 2‐amino‐4‐(9H‐carbazole‐3‐yl)thiophene‐3‐carbonitriles from preliminary carbazole ( 1 ) through an intermediate of 2‐(1‐(9H‐carbazole‐3‐yl)ethylidene)malononitriles using the Knoevenagel condensation followed by the Gewald reaction. On the other hand, the target compounds could also be prepared in a one‐pot three‐component manner by treating equimolar quantities of 1‐(9H‐carbazole‐3‐yl)ethanone ( 3 ), malononitrile, and elemental sulfur. The merits of this preparation are mild reaction conditions. The Gewald reaction is executed with inorganic base NaHCO₃ (H₂O) in tetrahydrofuran, easy work‐up procedure with good yields.     

Copper‐catalyzed Synthesis of N‐alkylated 2‐(4‐substituted‐1H‐1,2,3‐triazol‐1‐yl)‐1H‐indole‐3‐carbaldehyde by Step‐wise and One‐pot Three‐component Huisgen's 1,3‐dipolar Cycloaddition Reaction

An efficient method for the synthesis of N‐alkylated 2‐(4‐substituted‐1H‐1,2,3‐triazol‐1‐yl)‐1H‐indole‐3‐carbaldehyde has been developed starting from oxindole and indole using Huisgen's 1,3‐dipolar cycloaddition reaction of organic azides to alkynes. The effect of catalysts and solvent on these reactions has been investigated. Among all these conditions, while using CuSO₄·5H₂O, DMF was found to be the best system for this reaction. It could also be prepared in a one‐pot three‐component manner by treating equimolar quantities of halides, azides, and alkynes. The Huisgen's 1,3‐dipolar cycloaddition reaction was performed using CuSO₄·5H₂O in DMF with easy work‐up procedure.     

Iodotrimethylsilane‐Accelerated One‐Pot Synthesis of 5‐Unsubstituted 3,4‐Dihydropyrimidin‐2(1H)‐ones: A Novel Procedure for the Biginelli‐Like Cyclocondensation Reaction at Room Temperature

A novel Biginelli‐like cyclocondensation reaction is efficiently catalyzed by iodotrimethylsilane (Me₃SiI) in MeCN. The reaction proceeds at room temperature by a three‐component one‐pot condensation of ketones with aldehydes and urea to afford 5‐unsubstituted 3,4‐dihydropyrimidin‐2(1H)‐ones in good yields (Scheme 1 and Table).     

One—Pot Synthese of 3,4—Dihydropyrimidine—2（1H）—thiones Catalyzed by La（OTf）3

A general and practical procedure for the syntheses of 3,4-di-hydropyrimidine-2(1H)-thiones by a one-pot condensation of aldehyde,β-ketoester or β-diketone and thiourea using La(OTf)3 as the catalyst is described.Mild reaction conditions,excellent yields as well as the environmentally friendly character of La(OTf)3 make it an important alternative to the classic acid-catalyzed Biginelli‘s reaction.     

One‐Pot Synthesis of 2‐Substituted 4‐Aryl‐4,5‐dihydro‐3,1‐benzoxazepines from 2‐(2‐Aminophenyl)‐1‐arylethanols via Dehydration of the Corresponding Amides

An efficient method for the preparation of 2‐substituted 4‐aryl‐4,5‐dihydro‐3,1‐benzoxazepine derivatives under mild conditions has been developed. The reaction of 2‐(2‐aminophenyl)ethanols 1 with acid chlorides in the presence of excess Et₃N in THF at room temperature gave the corresponding N‐acylated intermediates 2 , which were dehydrated by treatment with POCl₃ to give 2‐substituted 4‐aryl‐4,5‐dihydro‐3,1‐benzoxazepines 3 in a one‐pot reaction.     

Efficient One‐Pot Access to 2,9‐Dihydrothiopyrano[2,3‐b]indole Scaffolds Showing Large Stokes Shifts

A simple, mild and efficient one‐pot approach for the construction of 2‐aryl‐3‐nitro‐2,9‐dihydrothiopyrano[2,3‐b]indole derivatives has been realized in CH₂Cl₂ medium at ambient temperature via three‐component tandem reaction of N‐protected‐2‐chloro‐3‐formylindoles, sodium hydrosulfide and β‐substituted nitroolefins/δ‐substituted nitrodienes using DABCO (10 mol%) as an organocatalyst, followed by dehydration in the presence of activated molecular sieves (4 Å). The significant advantages of this protocol are simple operation, shorter reaction time, high atom economy, good to high yields (73% –89%) and wider substrate scope. In addition, all the synthesized compounds have shown the large positive Stokes shift values (5632–6081 cm^?1).     

Stereochemical assignments of aldol products of 2‐arylimino‐3‐aryl‐thiazolidine‐4‐ones by 1H NMR

The aldol reactions of 2‐arylimino‐3‐aryl‐thiazolidine‐4‐ones with benzaldehyde carried out at ?78 °C were found to produce sec‐carbinols. Intramolecular hydrogen bonding within the aldol products forming a six‐membered ring enabled the assignment of stereochemistries of the major and minor diastereomers via analysis of the syn and anti ³J_H,H ¹H NMR coupling constants. Copyright © 2012 John Wiley & Sons, Ltd.     

One‐Pot Synthesis of 3‐Acetyl‐2‐aryl‐3,4‐dihydroquinazolines from N‐[2‐(Azidomethyl)phenyl]benzamides Utilizing Intramolecular Aza‐Wittig Reaction

A new and convenient method for the preparation of 3,4‐dihydroquinazolines 5 with aryl and Ac groups at C(2) and N(3), respectively, has been developed. The key sequence is the formation of aza‐phosphorane intermediates by the reaction of N‐[2‐(azidomethyl)phenyl]benzamides 1 with Ph₃P, followed by intramolecular aza‐Wittig reaction and 3‐acetylation, which can be conducted in one‐pot.     

Facile One‐pot Synthesis of Substituted Dihydropyrrol‐2‐ones via Four‐component Domino Reaction of Amines,Dialkyl Acetylenedicarboxylates and Formaldehyde

A mild and efficient method for the one‐pot synthesis of substituted dihydropyrrol‐2‐one derivatives is described via four‐component domino reaction of amines, dialkyl acetylenedicarboxyaltes and formaldehyde in the presence of 1‐methyl‐2‐oxopyrrolidinium hydrogen sulfate ([Hpyro][HSO₄]) as ionic liquid catalyst. This facile approach proceeded smoothly in good to high yields and pure products are separated from the reaction mixture by simple filtration.     

A Novel,One‐Pot Four‐Component Route to 2′‐Thioxo‐2′,3′‐dihydrospiro[indole‐3,6′‐[1,3]thiazin]‐2‐one Derivatives

An efficient route to 2′,3′‐dihydro‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives is described. It involves the reaction of isatine, 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ⁵‐phosphanylidene)ethan‐1‐one, and different amines in the presence of CS₂ in dry MeOH at reflux (Scheme 1). The alkyl carbamodithioate, which results from the addition of the amine to CS₂, is added to the α,β‐unsaturated ketone, resulting from the reaction between 1‐phenyl‐2‐(1,1,1‐triphenyl‐λ⁵‐phosphanylidene)ethan‐1‐one and isatine, to produce the 3′‐alkyl‐2′,3′‐dihydro‐4′‐phenyl‐2′‐thioxospiro[indole‐3,6′‐[1,3]thiazin]‐2(1H)‐one derivatives in excellent yields (Scheme 2). Their structures were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses.