Synthesis of a novel bifunctional oxyammonium-based ionic liquid: Application for the synthesis of pyrano[4,3-b]pyrans and tetrahydrobenzo[b]pyrans

In the present investigation, a novel bifunctional oxyammonium-based ionic liquid, namely, 2,2′-(ethane-1,2-diylbis[oxy])bis(ethan-1-aminium)-2,2,2-trifluoroacetate, was designed and synthesized. The structure of the titled ionic liquid was characterized using Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (¹HNMR), carbon nuclear magnetic resonance (¹³CNMR), fluorine nuclear magnetic resonance (¹⁹FNMR), homonuclear COSY nuclear magnetic resonance (NMR), thermogravimetry (TG), derivative thermogravimetry (DTG) analysis, X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The described ionic liquid demonstrated robust catalytic performance in the synthesis of pyrano[4,3-b]pyrans and tetrahydrobenzo[b]pyran derivatives. The ionic liquid presents a high potential of recycling and reusing capability in both types of model reactions.     

Condition based divergence in synthesis of tetrahydrobenzo[b]pyrans

Research on Chemical Intermediates - An environmentally benign novel strategy is developed for the synthesis of tetrahydrobenzo[b]pyrans by using thiamine mononitrate as a green catalyst, with the...     

A new synthesis of 1,2,3,5‐tetrahydroimidazo[2,3‐b]‐[1,3]benzodiazocines

A new synthesis of 6‐carbomethoxy‐1,2,3,5‐tetrahydroirnidazo[2,3‐b][1,3]benzodiazocines 13 by the intramolecular cycloaddition reaction of methyl 2‐(1‐aziridinylmethyl)‐3‐(2‐ureidophenyl)propenoates 10 under Appel's dehydration conditions is described. The latter were readily obtained from 2‐nitrobenzalde‐hyde with methyl acrylate through the Baylis‐Hillman reaction.     

2‐Nitroso‐1,3‐diphenyl‐1,2,3,4‐tetrahydrobenzo[b][1,6]naphthyridine

The title compound, C₂₄H₁₉N₃O, crystallizes in the centrosymmetric space group P2₁/a with one mol­ecule in the asymmetric unit. The tetra­hydro­pyridine ring has a boat conformation. The dihedral angle between the fused pyridine rings is 16.2 (1)°. The equatorial and axial orientations of the two phenyl groups with respect to the tetra­hydro­pyridine ring are confirmed. The nitroso group is coplanar with the attached C—N—C group. The interplanar angle formed between the fused tetra­hydro­pyridine and benzene planes is 13.4 (1)°. The crystal packing is stabilized by an intermolecular C—H⃛O hydrogen bond, which forms a C(9) graph‐set chain running along the [001] direction.     

Synthesis of 2‐amino‐4‐aryl‐7,7‐dimethyl‐5‐oxo‐4H‐5,6,7,8‐tetrahydrobenzo[b]pyran derivatives in ionic liquid medium

In this paper, preparation of 2‐Amino‐4‐aryl‐7,7‐dimethyl‐5‐oxo‐4H‐5,6,7,8‐tetrahydrobenzo[b]pyran derivatives from aromatic aldehyde, malononitrile or cyanoacetate and 5,5‐dimethyl‐1,3‐cyclohexanedione in ionic liquid [bmim⁺][BF₄^?] was described. Compared with other methods, this new method has the advantages of easier work‐up, milder reaction conditions, high yields and environmentally benign procedure.     

Efficient synthesis of α‐aminophosphonates via one‐pot reactions of aldehydes,amines, and phosphates in ionic liquid

Ionic liquids such as 1,3‐dialkylimidazolium bromides make excellent solvents for synthesis of α‐aminophosphonates from aldehydes, amines, and phosphites. The ionic liquids are successfully regenerated and reused. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:625–629, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20724     

N,N‐dimethylamino‐functionalized basic ionic liquid catalyzed one‐pot multicomponent reaction for the synthesis of 4H‐benzo[b]pyran derivatives under solvent‐free condition

A simple, clean, and environmentally benign three‐component process for the synthesis of 4H‐benzo[b]pyran derivatives using basic ionic liquid N,N‐dimethylaminoethylbenzyldimethylammonium chloride ([PhCH₂Me₂N⁺CH₂CH₂NMe₂]Cl⁻) as an efficient catalyst under solvent‐free condition is described. A wide range of aromatic aldehydes easily undergoes condensation with malononitrile and 5,5‐dimethylcyclohexane‐1,3‐dione (dimedone) 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 workup, and good yields. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:91–94, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20516     

An Efficient synthesis of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives via multicomponent reactions in ionic liquid

A series of pyrimido[4,5‐b]quinoline and indeno[2′,1′:5,6]pyrido[2,3‐d]pyrimidine derivatives were synthesized via the three‐component reaction of an aldehyde, 6‐aminopyrimidine‐2,4‐dione and 5,5‐dimethyl‐1,3‐cyclohexanedione or 1,3‐indanedione in ionic liquid 1‐n‐butyl‐3‐methylimidazolium bromide ([bmim]Br). This protocol has the advantages of easier work‐up, milder reaction conditions, high yields and an environmentally benign procedure compared with other methods.     

The reaction of 2‐amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]‐thiophene with diethyl malonate: synthesis of coumarin,pyridine, and thiazole derivatives

The reaction of 2‐amino‐3‐cyano‐4,5,6,7‐tetrahydrobenzo[b]thiophene ( 1 ) with diethyl malonate ( 2 ) gave two products: 3 and 4 . The reactivity of 3 toward a variety of chemical reagents was studied to give azoles, azines, and their fused derivatives. © 2001 John Wiley & Sons, Inc. Heteroatom Chem 12:168–175, 2001     

Convenient and Efficient Synthesis of 11‐Amino‐2,8‐substituted‐2,3,8,9‐tetrahydrobenzo[4,5]thieno[2,3‐b]quinolinone Derivatives

The Gewald reactions of 5‐substituted‐1,3‐cyclohexanedione, malononitrile, and powdered sulfur were carried out to give the corresponding products 2‐amino‐5‐substituted‐7‐oxo‐4,5,6,7‐tetrahydrobenzo[b]thiophene‐3‐carbonitrile derivatives 1 . The intermediate enamines 2 were prepared by reaction of compounds 1 and 5‐substituted‐1,3‐cyclohexanedione with hydrochloric acid as catalyst. The title compounds 11‐amino‐2,8‐substituted‐2,3,8,9‐tetrahydrobenzo[4,5]thieno[2,3‐b]quinolinone 3 were synthesized by cyclization of compounds 2 in the presence of K₂CO₃ and Cu₂Cl₂. The structures of all compounds were characterized by elemental analysis, IR, MS, and ¹H‐NMR spectra.     

A Mild and Efficient Synthesis of Novel Isoxazolyl‐Benzo[d]Pyrazino[2,1‐b] [1,3]Oxazoles

Synthesis of novel 2‐3‐methyl‐5‐[(E)‐2‐aryl‐1‐ethenyl]‐4‐isoxazolyl‐4,10a‐diaryl‐1,10a‐dihydro‐2H‐benzo[d]pyrazino[2,1‐b][1,3]oxazoles 5 were simply achieved by the reaction of 2‐[3‐methyl‐5‐[(E)‐2‐aryl‐1‐ethenyl]‐4‐isoxazolyl(2‐oxo‐2‐arylethyl)amino]‐1‐aryl‐1‐ethanones 3 with o‐aminophenol 4 in the presence of CAN catalyst. The intermediates, 2‐[3‐methyl‐5‐[(E)‐2‐aryl‐1‐ethenyl]‐4‐isoxazolyl(2‐oxo‐2‐arylethyl)amino]‐1‐aryl‐1‐ethanones 3 , were prepared by the reaction of 4‐amino‐3‐methyl‐5‐styrylisoxazole 1 , with phenacylbromides 2 in ethanol in the presence of K₂CO₃. The structures of the newly synthesized compounds 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l and 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 5k , 5l have been confirmed by analytical and spectral data.     

Phenylboronic acid as an efficient and convenient catalyst for a three-component synthesis of tetrahydrobenzo[b]pyrans

Phenylboronic acid, a non-toxic compound, is used as catalyst for an efficient, rapid, and one-pot three-component synthesis of tetrahydrobenzo[b]pyrans in good to excellent yields. This new procedure has the advantages of operational simplicity, shorter reaction time, higher yields and minimum pollution of the environment.     

Facile pathway for synthesis of two efficient catalysts for preparation of 2-aminothiophenes and tetrahydrobenzo[b]pyrans

Research on Chemical Intermediates - We report here a new magnetically recyclable catalyst consisting of iron-substituted Keggin-type heteropolyacid (HPA) grafted on modified Fe3O4 nanoparticles....     

Caffeine catalyzed green synthesis of novel benzo[a] [1,3]oxazino[6,5-c]phenazines via a one-pot multi-component sequential protocol in a basic ionic liquid

Caffeine was applied as a green and natural catalyst for the one-pot, four-component sequential condensation between 2-hydroxy-1,4-naphthoquinone, aromatic 1,2-diamines, ammonium thiocyanate and acid chlorides in the presence of a basic ionic liquid (1-butyl-3-methylimidazolium hydroxide) to afford the corresponding benzo[a] [1,3]oxazino[6,5-c]phenazine derivatives. In this one-pot transformation, five bonds and two new rings are efficiently formed. This protocol has the advantages of operational simplicity, high yields, easy workup, avoidance of hazardous or toxic catalysts and organic solvents and high chemo- and regioselectivities.