One‐Pot Three‐Component Synthesis of Benzo[f]thiopyrano[3,4‐b]quinolin‐11(8H)‐one Derivatives

A series of novel benzo[f]thiopyrano[3,4‐b]quinolin‐11(8H)‐one derivatives were synthesized via the reaction of aryl aldehyde, 2H‐thiopyran‐3,5(4H,6H)‐dione, and β‐naphthylamine in glacial acetic acid. This protocol features mild reaction conditions, high yields, and short reaction time.     

A Green Method for the Synthesis of Cyclopenta[b]chromen‐1(9H)‐one Derivatives in Ionic Liquids

A series of cyclopenta[b]chromen‐1(9H)‐one derivatives is prepared in high yields by a one‐pot reaction of substituted salicylaldehydes and cyclopentane‐1,3‐dione in ionic liquids of [BMIm]Br, the procedure is very mild and environmentally benign.     

Three‐component one‐pot synthesis of pyrazolo[3,4‐b]quinolin‐5(6H)‐one derivatives in aqueous media

A series of 4‐aryl‐3,7,7‐trimethyl‐1‐phenyl‐7,8‐dihydro‐1H‐pyrazolo[3,4‐b]quinolin‐ 5(6H)‐ones were synthesized by the three‐component reaction of aromatic aldehydes, 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐amine, and 5,5‐dimethyl‐1,3‐cyclohexandione in the presence of sodium 1‐dodecanesulfonate in aqueous medium. Compared to the previous methods, this new protocol has the advantages of convenient operation, higher yields, lower cost, and environmentally benign procedure. J. Heterocyclic Chem., (2012).     

Synthesis of New Chromeno[4,3‐b]pyrazolo[4,3‐e]pyridines Derivatives with Antimicrobial Evaluation

A series of 2‐oxo‐2,5‐dihydro‐1H‐chromeno[4,3‐b]pyridine derivatives were obtained by using a one‐pot three component reaction of 2,2‐disubstituted chroman‐4‐one with aromatic aldehydes and 2‐cyanoacetamide in the presence of sodium hydroxide under solvent‐free conditions. Heating chromenopyridine derivatives with phosphoryl chloride gave the corresponding chloro derivatives. The reaction of the chloro derivatives with hydrazine hydrate afforded dihydrochromeno[4,3‐b]pyrazolo[4,3‐e]pyridines derivatives. Condensation of the dimethyl derivative compound with the aromatic aldehydes gave 8‐Arylideneamino‐6,6‐dimethyl‐10H‐chromeno[4,3‐b]pyrazolo[4,3‐e]pyridine.     

An Efficient Synthesis of Chromeno[4,3‐d]isoxazolo[5,4‐b]pyridin‐6‐one Derivatives

A series of chromeno[4,3‐d]isoxazolo[5,4‐b]pyridin‐6‐one derivatives were easily and efficiently synthesized by the reaction of 3‐acyl‐2H‐chromen‐2‐ones with isoxazol‐5‐amine in acetic acid. Some synthesized compounds were evaluated for their antiproliferative properties in vitro against cancer cells, and these compounds were found to have some activities.     

An efficient synthesis of pyrazolo[3,4‐b]quinolin‐5(6H)‐one derivatives in ionic liquid

A series of 4‐aryl‐3,7,7‐trimethyl‐1‐phenyl‐7,8‐dihydro‐1H‐pyrazolo[3,4‐b]quinolin‐5(6H)‐ones were synthesized via the three‐component reaction of aromatic aldehydes, 5,5‐dimethyl‐1,3‐cyclohexandione and 5‐amino‐3‐methyl‐1‐phenylpyrazole in ionic liquid without using any catalyst. This protocol has the advantages of easier work‐up, milder reaction conditions, short reaction time, and environmentally benign procedure. J. Heterocyclic Chem., (2011).     

One‐pot Three‐component Synthesis of Spiro[pyrazolo[3,4‐b]pyridine‐4,3′‐indoline] Derivatives Catalyzed by Melamine Trisulfonic Acid

Novel spiro[pyrazolo[3,4‐b]pyridine‐4,3′‐indoline] derivatives were prepared by the three‐component reaction of isatins 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5‐amine and Meldrum's acid in the presence of a catalytic amount of melamine trisulfonic acid. This protocol provides a simple one‐step procedure with the advantages of easy work‐up, mild reaction conditions and environmentally benign.     

Efficient One‐Pot Synthesis of Spiro[indoline‐3,1′‐pyrazolo[1,2‐b] phthalazine] Derivatives via Three‐Component Reaction

An efficient one‐pot synthesis of spiro[indoline‐3,1′‐pyrazolo[1,2‐b]phthalazine] derivatives via three‐component reaction of phthalhydrazide, isatin, and malononitrile (cyanoacetic ester) is described. This new protocol has the advantages of high efficiency, mild reaction conditions, one‐pot procedure, and convenient operation.     

Improved and Efficient Synthesis of Chromeno[4,3‐d]pyrazolo [3,4‐b]pyridin‐6(3H)‐ones and Their Fluorescence Properties

A series of chromeno[4,3‐d]pyrazolo[3,4‐b]pyridin‐6(3H)‐one derivatives was easily and efficiently synthesized by the reaction of 2H‐chromen‐2‐ones with pyrazol‐5‐amines catalyzed by CuCl₂?2H₂O in ethanol. This protocol has the advantages of mild reaction conditions, easy work‐up, and high yields. These compounds were showed to have high fluorescence quantum yields, which mentioned their value as luminescence or fluorescence probe.     

One‐Pot Three‐Component Synthesis of 6H‐chromeno[4,3‐b] or Cyclopenta[b]furo[3,2‐f]quinoline Derivatives

Two series of furo[3,2‐f ]quinoline‐2‐carboxylate were obtained via a three‐component reaction of aldehydes, 5‐aminobenzofuran‐2‐carboxylate, and 4‐hydroxy‐2H‐chromen‐2‐one or cyclopentane‐1,3‐dione in DMF under catalyst‐free condition in high yields. This one‐pot three‐component reaction provided an efficient method for the synthesis of fused polycyclic heterocycles for bioactive screening.     

A Facile and Expeditious Microwave‐Assisted Synthesis of Furo[3,4‐b]indeno[2,1‐f]quinolin‐1‐one Derivatives via Multicomponent Reaction

A series of furo[3,4‐b]indeno[2,1‐f]quinolin‐1‐one derivatives were synthesized by the condensation of an aromatic aldehyde with tetronic acid and 9H‐fluoren‐2‐amine in solvent of glacial acetic acid under microwave irradiation. This procedure offers several advantages including operational simplicity, clean reaction, and increased safety for small‐scale high‐speed synthesis.     

Synthesis of Derivatives of Pyrido[4,3‐d]pyrimidin‐4(3H)‐one via an Iminophosphorane

A series of new, 2‐substituted 3‐aryl‐8,9,10,11‐tetrahydro‐5‐methyl[1]benzothieno[3′,2′ : 5,6]pyrido[4,3‐d]pyrimidin‐4(3H)‐ones, compounds 5a – q , were designed and synthesized via the aza‐Wittig reaction as the key step. The iminophosphorane 1 reacted with phenyl isocyanate (or 4‐chlorophenyl isocyanate) to the carbodiimide 4 , which was cyclized to 5 upon addition of different amines, EtOH, or phenols in the presence of a catalytic amount of EtONa or K₂CO₃ (Schemes 1 and 2). The structures of compounds 5 were confirmed by IR, ¹H‐ and ¹³C‐NMR, EI‐MS, elemental analyses, and, in the case of 5l , by single‐crystal X‐ray diffraction (Figure).     

A Green Synthesis of Pyrrolo[1,2‐a]quinazolin‐5(1H)‐one Derivatives in Ionic Liquids Catalyzed by Iodine

A series of 2,3,3a,4‐tetrahydro‐3a‐methylpyrrolo[1,2‐a]quinazolin‐5(1H)‐one derivatives were synthesized by a reaction of 2‐aminobenzamide and 5‐chloropentan‐2‐one at 80 °C catalyzed by iodine in ionic liquid of [BMIm]Br. Compared with the other methods, this novel method has the advantages of milder reaction conditions, high yields, environmental benignity, and metal‐free catalyst.     

Synthesis of New Furo[3,4‐b]quinolin‐1(3H)‐one Scaffolds Derived from γ‐Lactone‐Fused Quinolin‐4(1H)‐ones

In the context of our aim of discovering new antitumor drugs among synthetic γ‐lactone‐ and γ‐lactam‐fused 1‐methylquinolin‐4(1H)‐ones, we developed a rapid access to 5‐methyl‐1,3‐dioxolo[4,5‐g]furo[3,4‐b]quinoline‐8,9(5H,6H)‐dione ( 9 ) exploiting the γ‐lactone‐fused chloroquinoline 10 previously synthesized in our laboratory (Scheme 1). We also elaborated efficient synthetic methods allowing for a rapid access to two nonclassical bioisosteres of 9 , i.e., a deoxy and a carba analogue. The deoxy analogue 11 was prepared in two steps from the γ‐lactone‐fused quinoline 13 which was also the synthetic precursor of 10 (Scheme 1). The carba analogue 6,9‐dihydro‐5‐methyl‐9‐methylene‐1,3‐dioxolo[4,5‐g]furo[3,4‐b]quinolin‐8(5H)‐one ( 12 ) was easily prepared by HCl elimination from the 9‐(chloromethyl)dioxolofuroquinoline 15 , which was obtained via a three‐component one‐pot reaction from N‐methyl‐3,4‐(methylenedioxy)aniline (=N‐methyl‐1,3‐benzodioxol‐5‐amine; 16 ), commercially available chloroacetaldehyde, and tetronic acid ( 17 ) (Scheme 2).     

An Efficient Synthesis of 3H‐Pyrrolo[3,2‐d]pyrimidin‐4(5H)‐one Derivatives via an Iminophosphorane

The iminophosphorane ( 3 ), obtained from reaction of ethyl 3‐amino‐4‐cyano‐1‐phenyl‐1H‐pyrrole‐2‐carboxylate ( 2 ) with triphenylphosphine, hexachloroethane, and triethylamine, reacted with aromatic isocyanates to give carbodiimides ( 4 ). Further reaction of 4 with various amines, phenols, or ROH to give 2,3,5,7‐tetrasubstituted 3H‐pyrrolo[3,2‐d]pyrimidine‐4(5H)‐ones ( 6 ) in satisfactory yields in the presence of catalytic amount of sodium alkoxide or solid potassium carbonate.     

Synthesis and Structure of 2‐Substituted Thieno[3′,2′:5,6]pyrido[4,3‐d]pyrimidin‐4(3H)‐one Derivatives

A series of new 2‐substituted 3‐(4‐chlorophenyl)‐5,8,9‐trimethylthieno[3′,2′: 5,6]pyrido[4,3‐d]pyrimidin‐4(3H)‐ones 8 were synthesized via an aza‐Wittig reaction. Phosphoranylideneamino derivatives 6a or 6b reacted with 4‐chlorophenyl isocyanate to give carbodiimide derivatives 7a or 7b , respectively, which were further treated with amines or phenols to give compounds 8 in the presence of a catalytic amount of EtONa or K₂CO₃. The structure of 2‐(4‐chlorophenoxy)‐3‐(4‐chlorophenyl)‐5,8,9‐trimethylthieno[3′,2′: 5,6]pyrido[4,3‐d]pyrimidin‐4(3H)‐one ( 8j ) was comfirmed by X‐ray analysis.     

Synthesis of New 2‐Phenylpyrano[3,2‐b]phenothiazin‐4(6H)‐one Derivatives

A new synthesis of 2‐phenylpyrano[3,2‐b]phenothiazin‐4(6H)‐one derivatives was reported. First 2,10‐diacetyl‐3‐hydroxyphenothiazine ( 2 ) was converted into their benzoyloxy esters ( 3a – 3j ) using different aromatic carboxylic acids in the presence of phosphorous oxychloride in pyridine. Benzoyloxy esters were converted into their 1,3‐diones ( 4a – 4j ) by using dry KOH in pyridine via Baker‐Venkataraman transformation reaction. The 1,3‐diones thus obtained were cyclised to pyranophenothiazines ( 5a – 5j ) by refluxing in an acetic acid/HCl mixture.     

Ring closure reactions of 3‐arylhydrazonoalkyl‐quinolin‐2‐ones to 1‐aryl‐pyrazolo[4,3‐c]quinolin‐2‐ones

4‐Hydroxy‐3‐arylhydrazonoalkyl‐2‐quinolones 6 or reactive derivatives such as 3‐arylhydrazonoalkyl‐4‐tosyloxy‐2‐quinolones 7 or 4‐chloro‐3‐arylhydrazonoalkyl‐2‐quinolones 14 , which are obtained via 3‐acyl‐4‐hydroxyquinolones 4, 10 or 3‐phenylarrmomethylene‐quinoline‐2,4‐diones 12 , cyclize in excellent yields to 1‐aryl‐pyrazolo[4,3‐c]quinolin‐4‐ones (11). The cyclization conditions were investigated by differential scanning calorimetry (DSC).     

An Efficient Synthesis of Pyrrolo[1,2‐a] or Pyrido[1,2‐a]benzo[4,5]imidazo[1,2‐c]quinazoline Derivatives in Ionic Liquids Catalyzed by Iodine

2‐(1H ‐benzo[d ]imidazol‐2‐yl)anilines reacted with haloketones including 5‐chloropentan‐2‐one and 6‐chlorohexan‐2‐one catalyzed by iodine, giving benzo[4,5]imidazo[1,2‐c ]pyrrolo[1,2‐a ]quinazoline and 6H ‐benzo[4,5]imidazo[1,2‐c ]pyrido[1,2‐a ]quinazoline derivatives, respectively. This domino‐type reaction formed two new heterocycles and three new covalent bonds in one‐pot procedure and provided a green method for the synthesis of fused pentacyclic heterocycles bearing both quinazoline and benzimidazole moieties in ionic liquids.