Phenylphosphinic acid‐catalyzed synthesis of 6‐unsubstituted dihydropyrimidinones under solvent‐free conditions

Phenylphosphinic acid is found to catalyze the three‐component condensation of an aldehyde, enaminone, and urea or thiourea to afford the corresponding 6‐unsubstituted dihydropyrimidinones in high to excellent yields. This methodology is simple and fast synthetic route for the preparation of interesting class of heterocycles.     

One‐pot three components synthesis of alkyl indeno [1,2‐b]‐quinoxalin‐11‐ylideneacetates in water and under solvent‐free conditions

We introduced a very simple, one‐pot three component procedure for preparation of alkyl indeno[1,2‐b]quinoxalin‐11‐ylideneacetates 4 from reaction of ninhydrin 1 , phenylenediamines 2 , (alkoxycarbonylmethyl)triphenylphosphonium bromides 3 , and sodium acetate in water and under solvent‐free conditions. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:549–552, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20136     

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).     

1H and 13C NMR assignments of bioactive indeno[1,2‐b]indole‐10‐one derivatives

The complete ¹H and ¹³C assignments of eight bioactive indeno[1,2‐b]indole‐10‐one derivatives were accomplished by the combined use of one‐dimensional and two‐dimensional NMR experiments. Copyright © 2013 John Wiley & Sons, Ltd.     

Sulfamic acid: An efficient and green catalyst for synthesis of 1,5‐benzodiazepines under solvent‐free conditions

It is described that sulfamic acid can be utilized as an effective and green catalyst for the synthesis of 1,5‐benzodiazepines in high yields from the solvent‐free condensation of o‐phenylenediamine ( 1 ) and ketones ( 2 ). © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:354–358, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20305     

Synthesis of 12‐aryl‐12H‐benzo[i][1,3]‐dioxolo[4,5‐b]xanthene‐6,11‐diones using silica sulfuric acid as an efficient and versatile catalyst under solvent‐free conditions

Some novel 12‐aryl‐12H‐benzo[i][1,3]‐dioxolo[4,5‐b]xanthene‐6,11‐diones can be rapidly and efficiently synthesized in excellent yields by condensing a variety of aldehydes with 3,4‐methylenedioxyphenol and 2‐hydroxy‐1,4‐naphthoquinone in the presence of a catalytic amount of silica sulfuric acid under solvent‐free conditions. The simple experimental procedure, solvent‐free reaction conditions, utilization of an inexpensive and readily available catalyst, short period of conversion, and excellent yields are the advantages of the present method. Furthermore, the catalyst can be recycled and reused three times without significant loss of activity. The structures of the novel compounds are confirmed by IR, ¹H‐NMR, ¹³C‐NMR, MS, and elemental analysis. J. Heterocyclic Chem., 2011.     

Synthesis of 4H‐indeno[1,2‐b]thiophenes, 8H‐indeno[2,1‐b]‐thiophenes and 8H‐indeno[2,1‐b]furans having acrylic acid unit

Treatment of methyl propiolate and 2‐(thiophen‐2‐yl)benzaldehyde, 2‐(thiophen‐3‐yl)benzaldehyde or 2‐(furan‐3‐yl)benzaldehyde with tetrabutylammonium iodide/zirconium (IV) chloride or treatment of methyl acrylate and the same aldehydes with 1,4‐diazabicyclo[2,2,2]octane and triethanolamine induce an aldol‐type reaction to furnish Baylis‐Hillman adducts β‐iodo‐α‐(hydroxymethyl)acrylates or α‐(hydroxy‐methyl)acrylates, respectively. These can be used for the preparation of indenothiophenes and indenofurans having acrylic acid unit by intramolecular Friedel‐Crafts reaction with sulfuric acid in tetrachloromethane.     

Regioselective three‐component synthesis of novel indeno[1,2‐b]‐pyrazolo[4,3‐e]pyridines‐fused derivatives of 4‐azafluorenone alkaloid

New fused indeno[1,2‐b]pyridine derivatives have been prepared in a multicomponent reaction from benzaldehydes, indanedione and the appropriate aminoheteroaryl compound. The simple methodology permitted the syntheses of a series of indeno[1,2‐b]pyrazolo[4,3‐e]pyridines 4 from 5‐aminopyrazol 1 and modulated by the corresponding benzaldehyde 2 .     

Facile one‐pot synthesis of a series of 7‐aryl‐8H‐benzo[h]indeno[1,2‐b]quinoline‐8‐one derivatives catalyzed by cellulose‐based magnetic nanocomposite

A sulfonated magnetic cellulose‐based nanocomposite was applied as an efficient, inexpensive and green catalyst for the one‐pot three‐component synthesis of 7‐aryl‐8H ‐benzo[h ]indeno[1,2‐b ]quinoline‐8‐ones starting from 1,3‐indanedione, aromatic aldehydes and 1‐naphthylamine under solvent‐free conditions in high yields (79–98%) within short reaction times (2–5 min). The nanobiostructure catalyst can be easily separated from the reaction mixture by using an external magnet and reused several times.     

An efficient and clean one‐pot synthesis of 3,4‐dihydropyrimidine‐2(1H)‐ones catalyzed by tungstate sulfuric acid in solvent‐free conditions

Tungstate sulfuric acid catalyzes the three component condensation reaction of an aromatic aldehyde, urea and a β‐ketoester under solvent‐free conditions to afford the corresponding dihydropyrimidinones in high to excellent yields at room temperature.     

Microwave‐assisted synthesis of new regioisomeric 6,7‐dihydroindeno[1,2‐e]pyrimido[4,5‐b][1,4]diazepin‐5(5aH)‐ones

Novel 11‐amino‐6‐aryl‐6,7‐dihydroindeno[1,2‐e] pyrimido[4,5‐b][1,4]diazepin‐5(5aH)‐ones 4a‐f were prepared regioselectively by the tricomponent reaction of 4,5,6‐triaminopyrimidine 1, 1,3‐indandione 2 and aromatic aldehydes 3a‐f. The bicomponent approach, using 2,4,5,6‐tetraaminopyrimidine 5 and 2‐aryl‐ideneindandiones 6a‐f as reagents, afforded 9,11‐diamino‐6‐aryl‐6,7‐dihydroindeno[1,2‐e]pyrimido[4,5‐b]‐[1,4]diazepin‐5(5aH)‐ones 7a‐f in good yields and the regioisomeric 8,10‐diamino derivatives 8a‐c in lower yields. Both, bi‐ and tricomponent approaches were performed by microwave irradiation and all products were fully characterized by detailed NMR measurements.     

An efficient multicomponent and stereoselective synthesis of new spiro[indeno[1,2‐b]quinoxaline‐11,2′‐pyrrolidine] derivatives

New spiro[indeno[1,2‐b]quinoxaline‐11,2′‐pyrrolidine] derivatives were prepared in high yield stereoselectively from an efficient multicomponent 1,3‐dipolar cycloaddition reaction between ninhydrin, phenylenediamine, sarcosine, and chalcones. The regiochemistry and stereochemistry of resultant cycloadducts have been determined by several 2D NMR spectroscopic techniques and X‐ray single crystal diffraction. J. Heterocyclic Chem., (2012).     

Solvent‐free three‐component synthesis of 7‐aryl‐1,1‐dioxothieno[3,2‐b]pyran derivatives catalyzed by ammonium acetate

An efficient synthesis of 7‐aryl‐1,1‐dioxothieno[3,2‐b]pyran derivatives via the reaction of aryl aldehyde, tetrahydrothiophene‐3‐one‐1,1‐dioxide and malononitrile or ethyl 2‐cyanoacetate was performed at room temperature catalyzed by ammonium acetate under solvent‐free conditions. Compared with the conventional methods, this protocol features mild reaction conditions, high yields, and eco‐friendliness. J. Heterocyclic Chem., (2011).