Green Approaches for the Synthesis of 12-Aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones in Aqueous Media and Under Microwave Irradiation in Solventless Conditions

Convenient and environmentally benign procedures have been reported for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-one derivatives by multi component condensation reactions of aromatic aldehydes with β-naphthol and cyclic 1,3-dicarbonyl compounds, namely, dimedone and cyclohexane-1,3-dione. The three-component condensation has been successfully achieved in one pot by refluxing the components in water and is efficiently catalyzed by sulfuric acid. The condensation has also been achieved by irradiating the components in the presence of a catalytic amount of para-toluene sulfonic acid under neat conditions with microwaves. The green methodologies defined herein avoid the severe conditions posed by the older existing methods and prove to be efficient in terms of good yields, operational simplicity, easy workup, and short reaction time.     

Fe3O4 nanoparticles as an efficient and reusable catalyst for the solvent-free synthesis of 9,9-dimethyl-9,10-dihydro-8H-benzo-[a]xanthen-11(12H)-ones

A simple and efficient method for the synthesis of 9,9‐dimethyl‐9,10‐dihydro‐8H‐benzo‐[α]xanthen‐11(12)‐one derivatives (DDBXs) was developed by the condensation reaction of various substituted aryl al...     

Efficient one-pot syntheses of 2H-indazolo[2,1-b] phthalazine-triones by catalytic H2SO4 in water-ethanol or ionic liquid

Sulfuric acid-catalyzed, three-component, one-pot condensation of phthalhydrazide, aromatic aldehydes and 1,3-dicarbonyl compounds has been reported for the synthesis of a series of 2H-indazolo[2,1-b] phthalazine-triones in water-ethanol or in ionic liquid. The protocol proves to be efficient and environmentally benign in terms of high yields, low reaction times, ease of recovery, and reusability of reaction medium (ionic liquid).     

Fe_3O_4纳米粒子作为高效、可重复使用催化剂用于无溶剂条件下合成9,9-二甲基-9,10-二氢-8H-苯并[α]占吨11(12H)-酮（英文）

A simple and efficient method for the synthesis of 9,9‐dimethyl‐9,10‐dihydro‐8H‐benzo‐[α]xanthen‐11(12)‐one derivatives (DDBXs) was developed by the condensation reaction of various substituted aryl aldehydes with 2‐naphthol and dimedone using Fe3O4 magnetic nanoparticles (MNPs) as a heterogeneous catalyst under solvent‐free conditions at 90–110 °C.The experimental procedure is very simple,the products are formed in high yields and the catalyst is easily separated by applying an external magnetic field.     

A rapid and efficient method for the synthesis of 14H-dibenzo[α.j]xanthenes,aryl-5H-dibenzo[b.i]xanthene-5,7,12,14-(13H)-tetraone and 1,8-dioxooctahydroxanthenes by acidic ionic liquid

<正>Various xanthenes have been synthesized by the condensation ofβ-naphthol,2-hydroxynaphthalene-1,4-dione or dimedone with various aldehydes in the presence of trifluoroacetic acid as catalyst in 1,1,3,3-N,N,N′,N′-tetramethylguanidinium trifluoroacetate (TMGT) ionic liquid within 1 h at 75℃.     

A new green approach for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-one derivatives using task specific acidic ionic liquid[NMP]H_2PO_4

12-Aryl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-one derivatives were synthesized by a convenient and environmentally benign procedure involving multicomponent condensation reactions of substituted aromatic aldehydes with 2,7-dihydroxynaphthalene/2-naphthols/2,6-dihydroxynaphthlene and cyclic 1,3-dicarbonyl compounds in task specific acidic ionic liquid[NMP]H_2PO_4 at 80 ℃.This protocol has proved to be efficient in terms of good yields,operational simplicity,easy workup,recyclability of reaction medium/catalyst,and short reaction time.     

Efficient One-pot Synthesis of 12-Aryl-8, 9, 10, 12-tetrahydrobenzo[a]xanthen-11-ones Under Solvent-free Conditions

Multi-component condensation of 2-naphthol, aromatic aldehydes, and cyclic 1,3-dicarbonyl compounds catalyzed by ionic liquid [NSPTEA][HSO₄] was accomplished for the synthesis of a series of 12-aryl-8,9,10,12-tetrahydrobenzo[a]xanthen-11-ones under solvent-free conditions. High yields, ease recovery, short reaction time and reusability of catalyst are significant advantages. ZrOCl₂·8H₂O was also found to act as an effective catalyst towards this transformation.     

Sulfamic acid: a novel and efficient catalyst for the synthesis of aryl-14H-dibenzo[a.j]xanthenes under conventional heating and microwave irradiation

A simple and convenient procedure for the synthesis of aryl-14H-dibenzo[a.j]xanthenes is described through a one-pot condensation of β-naphthol with aryl aldehydes in the presence of sulfamic acid as the catalyst in a solvent-free media using both conventional heating and microwave irradiation.     

An unexpected multicomponent reaction leading to 2-arylpyrrolo[2,3,4-kl]acridin-1(2H)-ones

An unexpected condensation profile was observed for the three-component reaction of 5,5-dimethyl-1,3-cyclohexadione (dimedone), various anilines, and isatin leading to the synthesis of novel 2-arylpyrrolo[2,3,4-kl]acridin-1(2H)-ones in the ionic liquid [HMIm]HSO₄. Regeneration of the enamine group after the initial condensation reaction associated with participation of the restored amine group in translactonization with the pyrrolidone ring are suggested as the main differentiating events being favored over addition of the second dimedone molecule, with respect to similar reported reactions.     

A novel ionic liquid mediated synthesis of 4(1H)-quinolones, 5H-thiazolo[3,2-a]pyrimidin-5-one and 4H-pyrimido[2,1-b]benzothiazol-4-ones

A new, convenient, environmentally benign two-step synthesis of 4(1H)-quinolones, 5H-thiazolo[3,2-a]pyrimidin-5-one and 4H-pyrimido[2,1-b]benzothiazol-4-ones have been developed by first condensing substituted arylamine/2-aminothiazole/2-aminobenzenethiazole with Meldrum’s acid and trimethylorthoformate in 1-butyl-3-methylimidazolium bromide at a moderate temperature to afford 5-{(substituted aryl/4-methylthiazolyl/substituted benzothiazolyl)methylene}-2,2-dimethyl-1,3-dioxane-4,6-dione. The resulting compounds upon cyclization in 1-butyl-3-methyl tetrafluoroborate/triflate at a moderate temperature gave the title compounds in excellent yields.     

Ionic liquid promoted one-pot synthesis of 3-aminoimidazo[1,2-a]pyridines

3-Aminoimidazo[1,2-a]pyridines have been synthesized in good to excellent yields in the presence of the ionic liquid 1-butyl-3-methylimidazolium bromide [bmim]Br, the reaction workup is simple and the ionic liquid can be easily separated from the product and reused.     

One-pot synthesis of 12H-benzo[b]xanthen-12-ones and naphtha[2,3-b]furans from non-naphthalene substrates

An efficient one-pot synthesis of 12H-benzo[b]xanthen-12-ones via an oxidant initiated and base promoted tandem reaction of 2-(4-(2-haloaryl)-4-hydroxybut-1-ynyl)benzaldehydes has been developed. By using similar strategy, a one-pot synthesis of naphtha[2,3-b]furans from the cascade reaction of 2-(4-hydroxy-but-1-ynyl)benzaldehydes with 2-bromoacetonitrile or α-bromocarbonyl compounds has also been achieved.     

An efficient ionic liquid mediated synthesis of substituted 5H[1,3]-thiazolo[2,3-b]quinazoline-3,5-(2H)-dione and 5H-thiazolo[2,3-b]quinazolin-5-one

A new, environmentally benign two-step synthesis of 5H[1,3]-thiazolo[2,3-b]quinazoline-3,5-(2H)-dione and 5H-thiazolo[2,3-b]quinazolin-5-one derivatives has been accomplished stepwise. The substituted 2-aminobenzoic acid upon condensation with thiourea in 1-butyl-3-methylimidazolium bromide at moderate temperature under nitrogen atmosphere yielded 2-thioxo-1H-4-quinazolinones. The resulting intermediate 2-thioxo-1H-4-quinazolinones, when reacted with 2-chloroethanoic acid/2-chloropropanal underwent cyclization to yield the desired product in excellent yields.     

One-pot synthesis of various xanthene derivatives using ionic liquid 1, 3-disulfonic acid imidazolium hydrogen sulfate as an efficient and reusable catalyst under solvent-free conditions

In this study, 1,3-disulfonic acid imidazolium hydrogen sulfate （DSIMHS） is used as an efficient and reusable ionic liquid for the green, mild, and efficient synthesis of xanthenes under solvent-free conditions. Simple and easy work-up, low cost, green process, short reaction times and excellent yields of the products are the advantages of this procedure. Further, the catalyst can be recycled and reused at least for four times without a noticeably decrease in its catalytic activity.     

An efficient one-pot synthesis of tetrahydrobenzo[a]xanthene-11-one and diazabenzo[a]anthracene-9,11-dione derivatives under solvent free condition

Indium(III) chloride catalyzed one-pot synthesis of 12-aryl/alkyl-8,9,10,12-tetrahydrobenzo[a]xanthene-11-one and 8,10-dimethyl-12-aryl-8,12-dihydro-7-oxa-8,10-diazabenzo[a]anthracene-9,11-dione derivatives have been achieved by three component cyclocondensation of aldehydes, β-naphthol and cyclic 1,3-dicarbonyl compounds under solvent free condition in high yields. P₂O₅ too has been found as an effective catalyst towards this transformation.     

Copper-immobilized ionic liquid as an alternative to organic solvents in the one-pot synthesis of bioactive dihydropyrano[2,3-c]pyrazole derivatives

In this study, a novel Cu-immobilized ionic liquid (IL)was designed, characterized, and employed as both promoter and solvent in the synthesis of some dihydropyrano[2,3-c]pyrazoles. The synthesized ionic liquid was characterized by ¹H NMR, ¹³C NMR, FTIR, ICP and EDX analysis and showed high catalytic activity to proceed the synthesis of bioactive dihydropyrano[2,3-c]pyrazole derivatives. This method has the advantage of using the IL as a green medium for the synthesize of the products in high to excellent yields within short reaction times.     

Baylis-Hillman reaction in [bdmim][PF6] ionic liquid

A new use of ionic liquid [bdmim][PF₆] as solvent for the Baylis-Hillman reaction is presented. Unlike the commonly used [bmim][PF₆] that evidently reacts with electrophilic aldehydes under basic conditions, ionic liquid [bdmim][PF₆] is inert and the Baylis-Hillman reaction in [bdmim][PF₆] proceeds smoothly with better yield.     

One-pot synthesis of 7-aryl-11,12-dihydrobenzo[h]pyrimido-[4,5-b]quinoline-8,10(7H,9H)-diones via three-component reaction in ionic liquid

<正>A series of new 7-aryl-11,12-dihydrobenzo[h]pyrimido-[4,5-b]quinoline-8,10(7H,9H)-diones were synthesized via three-component reaction of aldehydes,l-naphthylamine and barbituric acid in ionic liquid.The method provided several advantages such as easy work-up,high yields and environmentally benign procedure.     

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.