Synthesiss of novel 3‐(2‐thienyl)‐1,2‐diazepino[3,4‐b]quinoxalines with algicidal activity

The reaction of the quinoxaline N‐oxide 1 with thiophene‐2‐carbaldehyde gave 6‐chloro‐2‐[1‐methyl‐2‐(2‐thienylmethylene)hydrazino]quinoxaline 4‐oxide 5 , whose reaction with 2‐chloroacrylonitrile afforded 8‐chloro‐2,3‐dihydro‐4‐hydroxy‐1‐methyl‐3‐(2‐thienyl)‐1H‐1,2‐diazepino[3,4‐b]quinoxaline‐5‐carbonitrile 6 . The reaction of compound 6 with various alcohols in the presence of a base effected alcoholysis to provide the 5‐alkoxy‐8‐chloro‐2,3,4,6‐tetrahydro‐1‐methyl‐4‐oxo‐3‐(2‐thienyl)‐1H‐1,2‐diazepino[3,4‐b]‐quinoxalines 7a‐d . The reaction of compounds 7a and 7b with diethyl azodicarboxylate effected dehydrogenation to give the 5‐alkoxy‐8‐chloro‐4,6‐dihydro‐1‐methyl‐4‐oxo‐3‐(2‐thienyl)‐1H‐1,2‐diazepino[3,4‐b]‐quinoxalines 8a and 8b , respectively. Compounds 8a and 8b were found to show good algicidal activities against Selenastrum capricornutum and Nitzchia closterium.     

Synthesis of N1‐substituted coumarino[4,3‐c] pyrazoles

3‐Acyl‐4‐hydroxy‐2‐oxo‐2H‐chromen derivatives 1a‐d were condensed with (7‐hydroxy‐2‐oxo‐2H‐chromen‐4‐yl)‐acetic acid hydrazide 2 , (4‐methyl‐2‐oxo‐2H‐chromen‐7‐yloxy)‐acetic acid hydrazide 3 , and (7‐hydrazinocarbonylmethoxy‐2‐oxo‐2H‐chromen‐4‐yl)‐acetic acid hydrazide 4 , to give corresponding 3‐alkyl‐1‐[2‐(7‐hydroxy‐2‐oxo‐2H‐chromeno‐4‐yl)‐acetyl]‐1H‐chromeno[4,3‐c]pyrazole‐4‐one 5a‐d , 3‐alkyl‐1‐[2‐(4‐methyl‐2‐oxo‐2H‐chromeno‐7‐yloxy)‐acetyl]‐1H‐chromeno[4,3‐c]pyrazole‐4‐one 6a‐d , and 1‐{4‐[(3‐alkyl‐1H‐chromeno[4,3‐c]pyrazole‐4‐one‐1‐yl)‐carbonylmethyl]‐2‐oxo‐2H‐chromen‐7‐yloxy‐acetyl}‐3‐alkyl‐1H‐chromeno[4,3‐c]pyrazole‐4‐one 7a‐d.     

Synthesis of novel pyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidines,pyrido[3″,2″:4′,5′]thieno[3′,2′:4,5]pyrimido[l,6‐a]benzimidazoles and related fused systems

3‐Amino‐4‐aryl‐5‐ethoxycarbonyl‐6‐methylthieno[2,3‐b]pyridine‐2‐carboxamides 3a‐c were prepared from ethyl 4‐aryl‐3‐cyano‐6‐methyl‐2‐thioxo‐1,2‐dihydropyridine‐5‐carbonylates 1a‐c and reacted with some carbonyl compounds to give tetrahydropyridothienopyrimidine derivatives 6a‐c, 7a‐c and 8a‐c , respectively. Treatment of compound 3c with chloroacetyl chloride led to the formation of a next key compound, ethyl 2‐chloromethyl‐4‐oxo‐3,4‐dihydropyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidine‐8‐carboxylate 9 . Also, 3‐amino‐2‐benzimidazolylthieno[2,3‐b]pyridine‐5‐carboxylate 5 and 2‐(3′‐aminothieno [2,3‐b]pyridin‐2′‐yl)‐4‐oxo‐3,4‐dihydropyrido[3′,2′:4,5]thieno[3,2‐d]pyrimidine‐8‐carboxylate 17 were prepared from 1c. The compounds 5, 9 and 17 were used as good synthons for other pyridothienopyrimidines and pyridothienopyrimidobenzimidazoles as well as for related fused polyheterocyclic systems.     

Studies with quinolines: New synthetic routes to 4H,5H,6H,9H‐benzo[ij]pyrano[2,3‐b]quinolizine‐8‐one, 4H‐pyrano[2,3‐b]pyridine, 2H‐pyran‐2‐one and pyranopyridoquinoline derivatives

Several new benzo[ij]pyrano[2,3‐b]quinolizine‐8‐ones 5 and 4H‐pyrano[2,3‐b]pyridine 8 derivatives were synthesized from 4‐hydroxyquinolines 1 . Reacting 3‐acetyl‐4‐hydroxy‐1‐phenyl‐1H‐quinoline‐2‐one with dimethylformamide dimethylacetal afforded 3‐(3‐Dimethylarnino‐acryloyl)‐4‐hydroxy‐1‐phenyl‐1H‐quinolin‐2‐one 9 . This reacted with hippuric acid and diethyl 3‐oxoglutarate to give 2H‐pyran‐2‐one 13 and pyranopyridoquinoline 17 respectively.     

Synthesis and reactions of 11H‐benzo[b]pyrano[3,2‐f]indolizines an pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolines

2‐Methyl‐3H‐indoles 1 cyclize with two equivalents of ethyl malonate 2 to form 4‐hydroxy‐11H‐benzo[b]pyrano[3,2‐f]indolizin‐2,5‐diones 3, whereas 2‐mefhyl‐2,3‐dihydro‐1H‐indoles 9 give under similar conditions regioisomer 8‐hydroxy‐5‐methyl‐4,5‐dihydro‐pyrrolo[3,2,1‐ij]pyrano[3,2‐c]quinolin‐7,10‐diones 10 . The pyrone rings of 3 and 9 can be cleaved either by alkaline hydrolysis to give 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 4 or 5‐acetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo‐[3,2,1‐ij]quinolin‐4‐ones 11 , respectively. Chlorination of 3 and 9 with sulfurylchloride gives under subsequent ring opening 7‐dichloroacetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 5 or 5‐dichloracetyl‐6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 12 . The dichloroacetyl group of 5 can be reduced with zinc to 7‐acetyl‐8‐hydroxy‐10H‐pyrido[1,2‐a]indol‐6‐ones 7. Treatment of the acetyl compounds 4, 7 and 11 with 90% sulfuric acid cleaves the acetyl group and yields 8‐hydroxy‐10H‐pyrido[1,2‐a]‐indol‐6‐ones 6 and 8 , and 6‐hydroxy‐2‐methyl‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 13 . Reaction of dichloroacetyl compounds 12 with sodium azide yields 6‐hydroxy‐2‐methyl‐5‐(1H‐tetrazol‐5‐ylcarbonyl)‐1,2‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinolin‐4‐ones 14 via intermediate geminal diazides.     

Novel Pyrano[2,3‐d]thiazole and Thiazolo[4,5‐b]pyridine Derivatives: One‐pot Three‐component Synthesis and Biological Evaluation as Anticancer Agents,c‐Met,and Pim‐1 Kinase Inhibitors

Preparation of pyrano[2,3‐d]thiazole and thiazolo[4,5‐b]pyridine derivatives through multicomponent reactions (MCRs) was achieved by the reaction of 2‐(2‐amino‐4,5,6,7‐tetrahydrobenzo[b]thiophen‐3‐yl)thiazol‐4(5H)‐one with various active methylene reagents such as ethyl cyanoacetate or malononitrile in basic conditions containing diverse aromatic aldehyde. Furthermore, this study aims to evaluate the in vitro cytotoxic activity of the synthetic compounds against six cancer cell lines, and all the prepared compounds revealed valuable activity compared with the CHS‐828, which is the 2‐[6‐(4‐chlorophenoxy)hexyl]‐1‐cyano‐3‐pyridin‐4‐ylguanidine as the standard drug. Some of the pyrano[2,3‐d]thiazole and thiazolo[4,5‐b]pyridine derivatives showed the highest antitumor activity towards the six cancer cell lines. Moreover, (c‐Met) enzymatic activity of the most potent compounds showed that compounds 3b 2‐(2‐amino‐4,5,6,7 tetrahydrobenzo[b]thiophen‐3‐yl)‐5‐hydroxy‐7‐(2‐hydroxy‐phenyl)‐7H‐pyrano[2,3‐d]thiazole‐6 carbonitrile and 5e 2‐(2‐amino‐4,5,6,7‐tetrahydrobenzo[b]thiophen‐3‐yl)‐5‐hydroxy‐7‐phenyl‐4,7‐dihydrothiazolo[4,5‐b]pyridine‐6‐carbonitrile were with higher activities than foretinib. Three compounds were selected to examine their Pim‐1 kinase where compounds 3b and 7b showed the highest inhibitions.     

Synthesis of Pyrano‐ and Pyrido‐Anellated Pyranosides as Precursors for Nucleoside Analogues

The push‐pull activated methyl (3Z)‐4,6‐O‐benzylidene‐3‐[(methylthio)methylene]‐3‐deoxy‐α‐D‐erythro‐hexopyranosid‐2‐ulose (1) reacted with dialkyl malonate in the presence of potassium carbonate to give the alkyl (2R,4aR,6S,10bS)‐4a,6,8,10b‐tetrahydro‐6‐methoxy‐8‐oxo‐2‐phenyl‐4H‐pyrano[3′,2′:4,5]pyrano[3,2‐d][1,3]dioxine‐9‐carboxylates 2 and 3. Treatment of 1 with 3‐oxo‐N‐phenyl‐butyramide, N‐(4‐methoxy‐phenyl)‐3‐oxo‐butyramide, and 3‐oxo‐N‐o‐tolyl‐butyramide, respectively, in the presence of potassium carbonate and 18‐crown‐6 yielded the (2R,4aR,6S,10bS)‐9‐acetyl‐7‐aryl‐4,4a,7,10b‐tetrahydro‐6‐methoxy‐2‐phenyl[1,3]dioxino‐[4′,5′:5,6]pyrano[3,4‐b]pyridin‐8(6H)‐ones 4–6. (2R,4aR,6S,10bS)‐4,4a,8,10b‐Tetrahydro‐6‐methoxy‐8‐oxo‐2‐phenyl‐4H‐pyrano[3′,2′:4,5]pyrano[3,2‐d][1,3]dioxine‐9‐carboxamide (7) was prepared by anellation reactions of 1 either with malononitrile or with cyanoacetamide.     

Quinolone analogues 8 [1‐6]. Synthesis of 3‐aminopyridazino‐[3,4‐b]quinoxalin‐4(lH)‐one

The 3‐amino‐1‐methylpyridazino[3,4‐b]quinoxalin‐4(1H)‐one 6 and N‐(1,4‐dihydro‐1‐methyl‐4‐oxopyridazino[3,4‐b]quinoxalin‐3‐yl)carbamates 17a,b were synthesized from the 1,4‐dihydro‐1‐methyl‐4‐oxopyridazino[3,4‐b]quinoxa‐line‐3‐carboxylate 1b via the 1,5‐dihydro‐4‐hydroxy‐1‐methylpyridazino[3,4‐b]quinoxaline‐3‐carbohydrazide 13b and then 1,4‐dihydro‐1‐methyl‐4‐oxopyridazino[3,4‐b]quinoxaline‐3‐carboxazide 8 . Heating of compound 13b and arylalde‐hydes afforded the 1,4‐dihydro‐1‐methyl‐4‐oxopyridazino[3,4‐b]quinoxaline‐3‐carbo(2‐arylmethylene)hydrazides 14a‐d.     

Reaction of cyclic imidates with α,β‐unsaturated esters: Synthesis of new pyrrolo[2,1‐b]‐1,3‐oxazine and pyrido[2,1‐b]‐1,3‐oxazine derivatives

The cycloaddition reaction of cyclic imidates, 2‐benzyl‐5,6‐dihydro‐4H‐1,3‐oxazines 1a , 1b , 1c , 1d , 1e , 1f , with dimethyl acetylenedicarboxylate 2 , trimethyl ethylenetricarboxylate 4 , or dimethyl 2‐(methoxymethylene)malonate 6 afforded new fused heterocyclic compounds, such as methyl (6‐oxo‐3,4‐dihydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐ylidene)acetates 3a , 3b , 3c , 3d , 3e , 3f (71–79%), dimethyl 2‐(6‐oxo‐3,4,6,7‐tetrahydro‐2H‐pyrrolo[2,1‐b]‐1,3‐oxazin‐7‐yl)malonates 5b , 5c , 5d , 5e , 5f (43–71%), or methyl 6‐oxo‐3,4‐dihydro‐2H,6H‐pyrido[2,1‐b]‐1,3‐oxazine‐7‐carboxylates 7a , 7b , 7c , 7d , 7e , 7f (32–59%), respectively. In these reactions, 1a , 1b , 1c , 1d , 1e , 1f (cyclic imidates, iminoethers) functioned as their N,C‐tautomers (enaminoethers) 2 to α,β‐unsaturated esters 2 , 4, and 6 to give annulation products 3 , 5 , and 7 following to the elimination of methanol, respectively. J. Heterocyclic Chem., (2011).     

Synthesis of Heteroannulated Chromeno[2,3‐b]Pyridines: DBU Catalyzed Reactions of 2‐Amino‐6‐methylchromone‐3‐Carboxaldehyde with Some Heterocyclic Enols and Enamines

New series of heteroannulated chromeno[2,3‐b]pyridines were easily and efficiently synthesized from DBU‐catalyzed condensation of 2‐amino‐6‐methylchromone‐3‐carboxaldehyde with a variety of heterocyclic enols and enamines, namely, 4‐hydroxycoumarin, 4‐hydroxy‐1‐methylquinolin‐2(1H)‐one, 2‐hydroxy‐4H‐pyrido[1,2‐a]pyrimidin‐4‐one, 4‐hydroxy‐2H‐pyrano[3,2‐c]quinoline‐2,5(6H)‐dione, 4(6)‐aminouracil and 5‐amino‐3‐methyl‐1H‐pyrazole. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.     

New approach to the synthesis of substituted 7H‐furo[3,2‐b]pyran‐7‐ones based on 5‐hydroxy‐2‐methyl‐4H‐pyran‐4‐one derivatives

A convenient approach to the synthesis of the previously unknown 7H‐furo[3,2‐b]pyran‐7‐ones based on the intramolecular cyclization of carbonyl derivatives of 5‐hydroxy‐2‐methyl‐4H‐pyran‐4‐one has been elaborated. Key intermediates in the synthesis of the target 7H‐furo[3,2‐b]pyran‐7‐ones are 3‐hydroxy‐6‐methyl‐2‐(2‐oxo‐2‐arylethyl)‐4H‐pyran‐4‐ones. They are formed as a result of multicomponent condensation of 5‐hydroxy‐2‐methyl‐4H‐pyran‐4‐one with arylglyoxals and 4‐methoxyaniline.     

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.     

Synthesis of Acetyl and Iodo Derivatives of 4‐Hydroxy‐6‐phenyl‐6H‐pyrano[3,2‐c]pyridine‐2,5‐diones and 4‐Hydroxy‐1‐phenylpyridin‐2(1H)‐ones

A simple and efficient method has been described for the synthesis of acetyl and iodo derivatives of 4‐hydroxy‐6‐phenyl‐6H‐pyrano[3,2‐c ]pyridine‐2,5‐diones 1 and 4‐hydroxy‐1‐phenylpyridin‐2(1H )‐ones 5 . Compounds 1 with phenyl and alkyl substituent at C(7) and C(8), respectively, can be easily acetylated by refluxing in a mixture of acetic acid and polyphosphoric acid to give 3‐acetyl‐4‐hydroxy‐6‐phenyl‐6H‐pyrano[3,2‐c ]pyridine‐2,5‐diones 2 in excellent yields. Compounds 1 and 5 can be iodinated with iodine and anhydrous sodium carbonate in boiling dioxane to give 4‐hydroxy‐3‐iodo‐6‐phenyl‐6H‐pyrano[3,2‐c ]pyridine‐2,5‐diones 3 and 4‐hydroxy‐3‐iodo‐1‐phenylpyridin‐2(1H )‐ones 6 , respectively, in good yields. The structures were confirmed using infrared, nuclear magnetic resonance , and elemental analysis.     

A novel and direct synthetic route to substituted 1,5‐dihydro‐4H‐[1]benzopyrano[4,3‐b]pyridine‐4,5‐diones

The condensation of 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one and substituted 2‐hydroxybenzaldehydes with ammonium acetate gave the title heterocycles. Synthesis of 1,5‐dihydro‐2‐methyl‐4H‐[1]naphtho‐[1′,2′:5,6]pyrano[4,3‐b]‐pyridine‐4,5‐dione is also described. A reaction mechanism is discussed.     

Synthesis of New Functionalized Heterocyclic [4,3,3] Propellanes via Three‐component Reaction Based on Ninhydrin–Phenol Adducts

Three‐component reaction between ninhydrin–phenol adducts, dialkyl acetylenedicarboxylates, and triphenylphosphine was investigated. Utilizing this protocol, dialkyl 10‐oxo‐10H‐4b,9b‐(epoxyethanooxy)indeno[1,2‐b]benzofuran‐12,13‐dicarboxylates as functionalized heterocyclic [4,3,3] propellanes was synthesized in 6‐endo‐trig cyclization mode. 8‐hydroxyquinoline showed serendipitous reactivity and produced para substituted adduct in the reaction with ninhydrin in acetic acid media and hence produced dialkyl 8a‐(4‐(alkoxycarbonyl)‐2‐oxo‐2H‐pyrano[3,2‐h]quinolin‐6‐yl)‐8‐oxo‐8,8a‐dihydro‐2H‐indeno[2,1‐b]furan‐2,3‐dicarboxylate in the reaction with dialkyl acetylenedicarboxylates and PPh₃.     

Quinolone analogues 2. A facile synthesis of novel 3‐substituted 1‐alkyl‐4‐oxo‐1,4‐dihydropyridazino[3,4‐b]quinoxalines

The reaction of the 2‐(1‐alkylhydrazino)‐6‐chloroquinoxaline 4‐oxides 1a,b with diethyl acetone‐dicarboxylate or 1,3‐cyclohexanedione gave ethyl 1‐alkyl‐7‐chloro‐3‐ethoxycarbonylmethylene‐1,5‐dihydropyridazino[3,4‐b]quinoxaline‐3‐carboxylates 5a,b or 6‐alkyl‐10‐chloro‐1‐oxo‐1,2,3,4,6,12‐hexahydroquinoxalino[2,3‐c]cinnolines 7a,b , respectively. Oxidation of compounds 5a,b with nitrous acid afforded the ethyl 1‐alkyl‐7‐chloro‐3‐ethoxycarbonylmethylene‐4‐hydroxy‐1,4‐dihydropyridazino‐[3,4‐b]quinoxaline‐4‐carboxylates 9a,b , whose reaction with base provided the ethyl 2‐(1‐alkyl‐7‐chloro‐4‐oxo‐1,4‐dihydropyridazino[3,4‐b]quinoxalin‐3‐yl)acetates 6a,b , respectively. On the other hand, oxidation of compounds 7a,b with N‐bromosuccinimide/water furnished the 4‐(1‐alkyl‐7‐chloro‐4‐oxo‐1,4‐dihydropyridazino[3,4‐b]quinoxalin‐3‐yl)butyric acids 8a,b , respectively. The reaction of compound 8a with hydroxylamine gave 4‐(7‐chloro‐4‐hydroxyimino‐1‐methyl‐1,4‐dihydropyridazino[3,4‐b]quinoxalin‐3‐yl)‐butyric acid 12 .     

Synthesis and Reactions of the Novel 6‐ethyl‐4‐hydroxy‐2,5‐dioxo‐5,6‐dihydro‐2H‐pyrano[3,2‐c]quinoline‐3‐carboxaldehyde

The novel 6‐ethyl‐4‐hydroxy‐2,5‐dioxo‐5,6‐dihydro‐2H‐pyrano[3,2‐c]quinoline‐3‐carboxaldehyde ( 2 ) was efficiently synthesized from Vilsmeier–Haack formylation of 3‐(1‐ethy1‐4‐hydroxy‐2‐oxo‐(1H)‐quinolin‐3‐yl)‐3‐oxopropanoic acid ( 1 ). The aldehyde 2 was allowed to react with some nitrogen nucleophiles producing a variety of hydrazones 3 – 7 . Reaction of aldehyde 2 with hydrazine hydrate and hydroxylamine hydrochloride afforded pyrazole and isoxazole annulated pyrano[3,2‐c]quinoline‐2,5(6H)‐dione, respectively. The reactivity of aldehyde 2 was examined toward some active methylene nitrile, namely, malononitrile, ethyl cyanoacetate, and cyanoacetamide leading to 2‐iminopyrano[2′,3′:4,5]pyrano[3,2‐c]quinolines 10 – 12 , respectively. Also, some novel pyrazolo[4″,3″:5′,6′]pyrano[2′,3′:4,5]pyrano[3,2‐c]quinolines ( 13 , 14 ) and thiazolo[5″,4″:5′,6′]pyrano[2′,3′:4,5]pyrano[3,2‐c]quinolines ( 15 , 16 ) were synthesized. Structures of the new synthesized products were deduced on the basis of their analytical and spectral data.     

Reaction of 6‐aryl‐ or styryl‐4‐methylsulfanyl‐2‐oxo‐2H‐pyrans with active methylene compounds and fluorescence properties of the products

New 2‐pyrone derivatives, dialkyl 3‐cyano‐6‐phenyl‐2‐oxo‐2H‐pyran‐4‐ylmalonates and alkyl 3‐cyano‐6‐phenyl‐2‐oxo‐2H‐pyran‐4‐ylacetates, which were easily prepared by the reaction of 6‐aryl‐4‐methyl‐sulfanyl‐2‐oxo‐2H‐pyran‐3‐carbonitriles with active methylene compounds in the presence of potassium carbonate, show fluorescence emission radiation. The light‐emitting region of dimethyl 3‐cyano‐6‐(4‐N,N‐dimethylamino)styryl‐2‐oxo‐2H‐pyran‐4‐ylmalonate ( 7h ) was 620 nm in dichloromethane, making this compound a typical red fluorescent compound. Methyl 8‐hydroxy‐6‐methyl‐1‐oxo‐3‐phenyl‐1H‐pyrano‐[3,4‐c]pyridine‐5‐carboxylate deriv‐atives also showed fluorescence in the solid state. This is the first example of fluorescence in fused 2‐pyrone derivatives.     

Synthesis of some novel fused oxo‐ and thiopyrimidines via an intramolecular friedel‐crafts reaction

1H‐Indeno[1,2‐d]pyrimidine‐2,5(3H,9bH)‐dione derivatives 2(a‐i) and 2,3‐dihydro‐2‐thioxo‐1H‐indeno[1,2‐d]pyrimidine‐5(9bH)‐ones 2(j‐q) were synthesized via an intramolecular Friedel‐Crafts reaction between the aryl and ester group of ethyl 6‐methyl‐4‐aryl‐2‐oxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carboxylates 1a‐i , and their thioxo analogs using AlCl₃ and acetyl chloride in nitrobenzene. Yields of the products, after washing with THF, were of the order of 45‐69%. IR and NMR spectroscopy together with elemental analysis were used for identification of these compounds.     

Design and Synthesis of Some Novel 2,3,4,5‐Tetrahydro‐1H‐pyrido[4,3‐b]indoles as Potential c‐Met Inhibitors

Since deregulation of the tyrosine‐kinase receptor c‐Met is implicated in several human cancers and is an attractive target for small‐molecule‐drug discovery, we report herein the synthesis of 2,3,4,5‐tetrahydro‐8‐[1‐(quinolin‐6‐ylmethyl)‐1H‐1,2,3‐triazolo[4,5‐b]pyrazin‐6‐yl]‐1H‐pyrido[4,3‐b]indoles 4a – 4c and 2,3,4,5‐tetrahydro‐8‐[3‐(quinolin‐6‐ylmethyl)‐1,2,4‐triazolo[4,3‐b]pyridazin‐6‐yl]‐1H‐pyrido[4,3‐b]indoles 5a – 5c . These indole derivatives demonstrated inhibition of c‐Met kinase activity. Concurrently, five key intermediates were synthesized. These compounds could be prepared in good yields.