A one-pot multicomponent reaction for the synthesis of 2-amino-2-chromenes promoted by <Emphasis Type="Italic">N,N</Emphasis>-dimethylamino-functionalized basic ionic liquid catalysis under solvent-free condition

Abstract  A simple, clean, and environmentally benign three-component process to the synthesis of 2-amino-4H-chromenes using N,N-dimethylaminoethylbenzyldimethylammonium chloride, [PhCH₂Me₂N⁺CH₂CH₂NMe₂]Cl⁻, as an efficient catalyst under solvent-free condition is described. A wide range of aromatic aldehydes easily undergo condensations with α-naphthol and malononitrile under solvent-free condition to afford the desired products of good purity in excellent yields. Taking into account environmental and economical considerations, the protocol presented here has the merits of environmentally benign, simple operation, convenient work-up and good yields. Furthermore, the catalyst can be easily recovered and reused for at least five cycles without losing its activities. Graphical abstract        

A one-pot multicomponent reaction for the synthesis of 2-amino-2-chromenes promoted by N,N-dimethylamino-functionalized basic ionic liquid catalysis under solvent-free condition

Abstract  

A simple, clean, and environmentally benign three-component process to the synthesis of 2-amino-4H-chromenes using N,N-dimethylaminoethylbenzyldimethylammonium chloride, [PhCH₂Me₂N⁺CH₂CH₂NMe₂]Cl⁻, as an efficient catalyst under solvent-free condition is described. A wide range of aromatic aldehydes easily undergo condensations with α-naphthol and malononitrile under solvent-free condition to afford the desired products of good purity in excellent yields. Taking into account environmental and economical considerations, the protocol presented here has the merits of environmentally benign, simple operation, convenient work-up and good yields. Furthermore, the catalyst can be easily recovered and reused for at least five cycles without losing its activities.     

Synthesis of 14‐{[(Un)substituted phenyl] or alkyl}‐14H‐dibenzo[a,j]xanthenes Using Yb(OTf)3 as an Efficient Catalyst under Solvent‐free Conditions

A series of 14‐{[(Un)substituted phenyl] or alkyl}‐14H‐dibenzo[a,j]xanthenes were prepared under solvent‐free conditions by Yb(OTf)₃ catalyzed condensation reactions of β‐naphthol with various aldehydes. The process presented here is operationally simple, environmentally benign and has good to excellent yields. Furthermore, the catalyst can be recovered conveniently and reused efficiently.     

Mixed metal MgO–ZrO2 nanoparticle‐catalyzed O‐tert‐Boc protection of alcohols and phenols under solvent‐free conditions

An environmentally benign method for O‐tert‐Boc protection of alcohols and phenols catalyzed by MgO–ZrO₂ nanoparticles under solvent‐free conditions is described. A variety of phenols, alcohols (aliphatic and aromatic) were converted to corresponding O‐tert‐Boc products in good to excellent yield (50–95%). The present protocol is expedient, simple, and efficient under solvent‐free conditions. The MgO–ZrO₂ Nps are easily prepared from inexpensive precursors, and are reusable, recyclable and chemoselective. Copyright © 2012 John Wiley & Sons, Ltd.     

Ionic Liquid Catalyzed One‐Pot Synthesis of 2H‐Pyridazino[1,2‐a]indazole‐1,6,9(11H)‐triones Via Three‐Component Reaction under Solvent‐Free Conditions

2H‐Pyridazino[1,2‐a]indazole‐1,6,9(11H)‐triones were synthesized through one‐pot, three‐component condesation of aldehydes, maleic hydrazide, and dimedone using a green and inexpensive Brönsted acidic ionic liquid 1‐methyl‐2‐pyrrolidinone hydrosulfate ([Hnmp]HSO₄) as catalyst under solvent‐free conditions. The method provided several advantages such as milder conditions, shorter reaction time, high yields, and environmentally benign procedure.     

Dicationic ionic liquids as recyclable catalysts for one‐pot solvent‐free synthesis of α‐aminophosphonates

Some task‐specific ionic liquids N,N,N′,N′‐tetramethyl‐N,N′‐dipropanesulfonic acid ethylene‐diammonium hydrogen sulfate, N,N,N′,N′‐tetramethyl‐N,N′‐dipropanesulfonic acid‐1,3‐propanediammonium hydrogen sulfate, N,N,N′,N′‐ tetramethyl‐N,N′‐ dipropanesulfonic acid‐1,6‐hexanediammonium hydrogen sulfate were prepared. These ionic liquids could be used as efficient and recyclable catalysts for the synthesis of α‐aminophosphonates at room temperature via an one‐pot three‐component reaction under organic solvent‐free conditions with good yields of 83–96%. The postprocessing was simple, and the catalysts could be reused at least six times without noticeably decreasing the catalytic activity. The novel clean procedure offers the advantages including short reaction time, good yields, operational simplicity, and environmentally benign. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:1–5, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20647     

Highly Efficient Direct Synthesis of Scaffold 9a,10,12,12a‐Tetrahydrobenzo[b]cyclopenta[f]pyrrolo[1,2‐d][1,4]diazepinone by Using Active Phoshomolybdic Acid

Domino coupling of furan‐2‐yl (phenyl) methanol and 2‐(1H‐pyrrol‐1‐yl) aniline has been achieved in the presence of 10 mol% phosphomolybdic acid in CH₃CN under reflux to afford the corresponding biologically active 10‐aryl‐9a,10,12,12a‐tetrahydrobenzo[b]cyclopenta[f]pyrrolo[1,2‐d][1,4]diazepin‐11(9H)‐ones in good yields. Broad substrate scope, short reaction times, environmentally benign, and operational simplicity makes this method more attractive.     

Tandem synthesis of 2,3‐dihydroquinazolin‐4(1H)‐ones on grinding under solvent‐free conditions

Citric acid promoted synthesis of a mini‐library 2,3‐dihydroquinazolin‐4(1H)‐ones with good to excellent yields is achieved by tandem reaction of anthranilamides (or anthranilhydrazides) with aldehydes on grinding at room temperature under solvent‐free conditions. This method has notable advantages in terms of simple workup, short reaction time, cost‐effective, and environmentally benign. J. Heterocyclic Chem., (2012).     

Catalyst‐free Synthesis of 5‐Arylimidazo[1,2‐c]quinazoline Derivatives in Ionic Liquids

The reaction of 2‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)aniline and aromatic aldehyde was treated in ionic liquids under catalyst‐free condition and gave dehydrogenated 5‐aryl‐2,3‐diphenylimidazo[1,2‐c ]quinazolines. The same reaction gave un‐aromatized 5‐aryl‐2,3‐diphenyl‐5,6‐dihydroimidazo[1,2‐c ]quinazoline derivatives while it was controlled in an inert gas. This procedure approach to imidazo[1,2‐c ]quinazolines has the advantages of milder reaction conditions, one‐pot, catalyst free, high yields, and environmentally benign.     

An Exceedingly Mild,Green Synthesis of Substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amine Derivatives and Their Antimicrobial Activity

An exceedingly and highly efficient procedure has been described for the synthesis of substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amines by the reaction of 2‐chloro‐3‐aryl‐1,8‐naphthyridines with various anilines in the presence of N‐methyl‐2‐pyrrolidone and K₂CO₃ under thermal green solvent‐free conditions. The significant features of this green reaction include very good yields in purity, simple experimental, short reaction time, easy workability, and avoidance of toxic solvents. All synthesized compounds have been evaluated for their antibacterial activity.     

Synthesis of 4‐substituted styrene compounds via palladium catalyzed Suzuki–Miyaura reaction using bidentate Schiff base ligands

Air‐stable symmetric Schiff base have been synthesized and proved to be efficient ligands for Suzuki–Miyaura reaction between aryl bromides and arylboronic acids using PdCl₂(CH₃CN)₂ as palladium source under aerobic conditions. The coupling reaction proceeded smoothly using N,N‐bis(anthracen‐9‐ylmethylene)benzene‐1,2‐diamine (L₇) as ligand to provide 4‐substituted styrene compounds in good yields. Copyright © 2009 John Wiley & Sons, Ltd.     

Molecular Iodine Catalyzed One‐pot Aza‐Diels‐Alder Reaction under Solvent‐free Conditions

Catalyzed by molecular iodine at room temperature, under solvent‐free conditions, a two component aza‐Diels‐Alder cyclization of N‐vinyl‐2‐pyrrolidinone with N‐arylimine gave tetrahydroquinoline derivatives in good yields and high stereo‐selectivity. And three components aza‐Diels‐Alder reaction of N‐vinyl‐2‐pyrrolidinone, anilines and indole‐3‐carbaldehydes under the same condition afford only cis‐product in good yields.     

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).     

Synthesis and Mechanistic Study of Triheterocyclic 4H‐Pyrimido[2,1‐b]benzothiazole derivatives,One‐Pot Three‐component Reaction under Solvent‐Free Conditions

An efficient method has been developed for the preparation of 4H‐pyrimido[2,1‐b]benzothiazole derivatives by the condensation of aldehydes, β‐ketoester, and 2‐amino benzothiazole under solvent and solvent‐free conditions using various catalysts. The reaction uses benzothiazole as a new component, and good yield is obtained at 60–65°C under solvent‐free conditions. Atom economies, good yield, environmentally benign, and easy to work‐up are some of the important features of this protocol. The present study suggests that acetic acid and metal catalysts follow different mechanism. In acetic acid, 2‐amino benzothiazole reacts with benzaldehyde, and resultant intermediate reacts with ethyl acetoacetate to give final product, whereas in the presence of metal catalysts, 2‐amino benzothiazole first reacts with ethyl acetoacetate, and resultant intermediate reacts with benzaldehyde to give pyrimido[2,1‐b]benzothiazole.     

One‐Pot Synthesis of 3‐[(N‐Alkylanilino)(aryl)methyl]indoles via a Transition Metal Assisted Three‐Component Condensation at Room Temperature

A simple and highly efficient protocol for the one‐pot synthesis of a series of 3‐[(N‐alkylanilino)(aryl)methyl]indoles has been developed based on low‐cost and environmentally benign zirconium oxychloride octahydrate and copper chloride dihydrate catalysts via three‐component condensation between indoles, aromatic aldehydes, and N‐alkylanilines at room temperature under neat condition. Mild reaction conditions, operational simplicity, high atom‐economy, good yields in relatively shorter reaction times, use of low‐cost and eco‐friendly catalysts are some of the salient features of this protocol.     

ESI‐MS studies of palladium (II) complexes with 1‐(p‐toluenesulfonyl)cytosine/cytosinato ligands

The mononuclear complex Pd(1‐TosC‐N3)₂Cl₂ (2) containing 1‐(p‐toluenesulfonyl)cytosine (1) as a ligand, as well as dinuclear complexes Pd₂(1‐TosC^?‐N3,N4)₄ (3) and Pd₂(1‐TosC^?‐N3,N4)₂DMSO₂Cl₂ (4) containing the ligand anion (1‐TosC^?), was mass analyzed by electrospray ionization ion trap MS/MS and high resolution MS. Complexes 3 and 4 were obtained by recrystallization of 2 from DMF and DMSO, respectively. The behavior of complex 2 in different solutions was monitored by electrospray ionization mass spectrometry (ESI‐MS). Under the applied ESI‐MS conditions, complex 2 in methanol reorganized itself dominantly as new complex 3 and the solvent did not coordinate the formed species. In H₂O/DMSO, CH₃CN/DMSO and CH₃OH/DMSO solutions, complex 2 formed several new species with solvent molecules involved in their structure, e.g. complex 4 was formed as the major product. The newly formed species were also examined by LC‐MS‐DAD, confirming the solvent induced reorganization and the solution instability of complex 2. Copyright © 2009 John Wiley & Sons, Ltd.     

Application of Sulfonic Acid Functionalized SBA‐15 as a New Nanoporous Acid Catalyst in the Green One‐Pot Synthesis of Spirooxindole‐4H‐pyrans

Sulfonic acid functionalized SBA‐15 (SBA‐Pr‐SO₃H) as a new nanoporous solid acid catalyst was applied in the green one‐pot synthesis of spirooxindole‐4H‐pyrans via condensation of isatins, malononitrile or methyl cyanoacetate or ethyl cyanoacetate, and 4‐hydroxycoumarin in water solvent. SBA‐Pr‐SO₃H was proved to be an efficient heterogeneous nanoporous solid acid catalyst with a pore size of 6 nm that could be easily handled and removed from the reaction mixture by simple filtration and can be recovered and reused for several times without any loss of activity. The significant merits of present methodology are its simplicity, short reaction time, good yields, and environmentally benign mild reaction condition as water was used as a green solvent.     

Synthesis and helical conformation of poly(N‐propargylamides) carrying L‐aspartic acid in the side chain

Aspartic acid‐based novel poly(N‐propargylamides), i.e., poly[N‐(α‐tert‐butoxycarbonyl)‐L ‐aspartic acid β‐benzyl ester N′‐propargylamide] [poly( 1 )] and poly[N‐(α‐tert‐butoxycarbonyl)‐L ‐aspartic acid α‐benzyl ester N′‐propargylamide] [poly( 2 )] with moderate molecular weights were synthesized by the polymerization of the corresponding monomers 1 and 2 catalyzed with (nbd)Rh⁺[η⁶‐C₆H₅B^?(C₆H₅)₃] in CHCl₃ at 30 °C for 2 h in high yields. The chiroptical studies revealed that poly( 1 ) took a helical structure in DMF, while poly( 2 ) did not in DMF but did in CH₂Cl₂, CHCl₃, and toluene. The helicity of poly( 1 ) and poly( 2 ) could be tuned by temperature and solvents. Poly( 2 ) underwent solvent‐driven switch of helical sense, accompanying the change of the tightness. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5168–5176, 2005     

Structure and Bonding in Bis(1‐naphthyl) Diselenide and Bis{[2‐(N,N‐dimethylamino)methyl]phenyl} Tetraselenide,and Their Brominated Derivatives

The formation and crystal structures of bis(1‐naphthyl) diselenide ( 1 ) and bis{[2‐(N,N‐dimethylamino)methyl]phenyl} tetraselenide ( 2 ) are described. Whereas 1 can be produced in good yields, 2 is formed only as a minor product together with the known main product, bis{[2‐(N,N‐dimethylamino)methyl]phenyl} diselenide. The composition of the reaction mixture is semi‐quantitatively estimated by ⁷⁷Se NMR spectroscopy and DFT calculations. The effect of the n²→σ*(Se–Se) and π→σ*(Se–Se) secondary bonding interactions on the Se–Se bonds is discussed both by DFT calculations and comparison with literature, as available. The bromination of 1 yields monomeric (1‐naphthyl)selenenyl bromide ( 3 ) in good yields. That of the reaction mixture of (C₆H₄CH₂NMe₂)Se_x (x = 2–4) and Se₈ afforded (C₆H₄CH₂NMe₂H)₂[SeBr₄] ( 4 ) and (C₆H₄CH₂NMe₂H)₂[SeBr₆] ( 5 ) in addition to (C₆H₄CH₂NMe₂)SeBr, which has been previously reported.     

Synthesis and characterizations of N,N′‐bis(diphenylphosphino)‐2‐(aminomethyl)aniline derivatives: application of a palladium(II) complex as pre‐catalyst in Heck and Suzuki cross‐coupling reactions

The reaction of 2‐(aminomethyl)aniline with 2 equivalents of PPh₂Cl in the presence of Et₃N, proceeds in CH₂Cl₂ to give N,N′‐bis(diphenylphosphino)‐2‐(aminomethyl)aniline 1 in good yield. Oxidation of 1 with aqueous H₂O₂, elemental sulfur or gray selenium gave the corresponding oxide, sulfide and selenide dichalcogenides [Ph₂P(E)NHC₆H₄CH₂NHP(E)Ph₂] (E: O, 2a; S, 2b; Se, 2c), respectively. The reaction of [Ph₂PNHC₆H₄CH₂NHPPh₂] with PdCl₂(cod), PtCl₂(cod) and [Cu(MeCN)₄]PF₆ gave the corresponding chelate complexes, PdCl₂1, PtCl₂1 and [Cu(1)₂]PF₆. The new compounds were fully characterized by NMR, IR spectroscopy and elemental analysis. The catalytic activity of the Pd(II) complex was tested in the Suzuki coupling and Heck reactions. The Pd(II) complex catalyzes the Suzuki coupling and Heck reaction, affording biphenyls and stilbenes respectively, in good yields. Copyright © 2009 John Wiley & Sons, Ltd.