A simple synthesis of 4‐chloro‐5‐hydroxy‐1H‐benzo[g]indoles

The reaction of methyl 2‐(3‐chloro‐1,4‐dioxo‐1,4‐dihydronaphthalen‐2‐yl)propenoate ( 2a ) with primary amines gave 4‐chloro‐5‐hydroxy‐3‐methoxycarbonyl‐1H‐benzo[g]indoles 5a‐f as major compounds and 3‐methoxycarbonyl‐4,9‐dioxo‐2,3,4,9‐tetrahydro‐1H‐benzo[f]indoles 6a‐d as minor ones. Whereas the reaction of 3‐(3‐chloro‐1,4‐dioxo‐1,4‐dihydronaphthalen‐2‐yl)‐3‐buten‐2‐one ( 2b ) with primary amines afforded the corresponding 1H‐benzo[g]indoles 5g‐i as major products and 3‐acetyl‐4,9‐dihydro‐4,9‐dioxo‐1H‐benzo[f]indoles 7g, h as minor products.     

Synthesis of 1,3,4‐Oxadiazole Acyclo C‐Nucleosides Bearing 5‐Methylthio{7‐substituted‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}moieties

Oxidative cyclization of the sugar hydrazones ( 3_a‐f ) derived from {7H‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐ylsulfanyl}acetic acid hydrazide ( 1 ) and aldopentoses 2_a‐c or aldohexoses 2_d‐f with bromine in acetic acid in the presence of anhydrous sodium acetate, followed by acetylation with acetic anhydride gave the corresponding 2‐(per‐O‐acetyl‐alditol‐l‐yl)‐5‐methylthio{7H‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}‐1,3,4‐oxadiazoles ( 5_a‐f ). Condensative cyclization of the sugar hydrazones ( 3_a‐f ) by heating with acetic anhydride gave the corresponding 3‐acetyl‐2‐(per‐O‐acetyl‐alditol‐1‐yl)‐2,3‐dihydro‐5‐methylthio{7‐acetyl‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}‐1,3,4‐oxadiazoles ( 11_a‐f ). De‐O‐acetylation of the acyclo C‐nucleoside peracetates ( 5 and 11 ) with methanolic ammonia afforded the hydrazono lactones ( 7 ) and the acyclo C‐nucleosides ( 12 ), respectively. The structures of new oxadiazole derivatives were confirmed by analytical and spectral data.     

Syntheses of Some 3—[1′（1′H）—Substituent—pyrazol—5′—yl] benzo [5,6] coumarins

3-[1′(1′H)-Substituent-pyrazol-5′-yl]benzo[5,6]coumarins and 3-(1′,2′-oxazol-5′-yl)benzo[5,6]coumarin were prepared via condensation of 3-(2′-formyl-1′-chlorovinyl)benzo[5,6] coumarin with hydrazine derivatives or hydroxylamine.Reaction of 3-[1′(1′H)-pyrazol-5′-yl]benzo[5,6]coumarin with alkyl halides,olefinic compunds or acid chlorides are described.     

Synthesis of New Derivatives of 4‐(4,7,7‐Trimethyl‐7,8‐dihydro‐6H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐2‐yl)morpholine

Cyclocondensation of 5‐amino‐6‐methyl‐2‐morpholinopyrimidine‐4‐thiol ( 1 ) and 2‐bromo‐5,5‐dimethylcyclohexane‐1,3‐dione ( 2 ) under mild reaction condition afforded 4,7,7‐trimethyl‐2‐morpholino‐7,8‐dihydro‐5H‐benzo[b ]pyrimido[5,4‐e ][1,4]thiazin‐9(6H )‐one ( 3 ). The ¹H and ¹³C NMR data of compound ( 3 ) are demonstrated that this compound exists primarily in the enamino ketone form. Reaction of compound ( 3 ) with phosphorous oxychloride gave 4‐(9‐chloro‐4,7,7‐trimethyl‐7,8‐dihydro‐6H‐benzo[b ]pyrimido[5,4‐e ][1,4]thiazin‐2‐yl)morpholine ( 4 ). Nucleophilic substitution of chlorine atom of compound ( 4 ) with typical secondary amines in DMF and K₂CO₃ furnished the new substituted derivatives of 4‐(4,7,7‐trimethyl‐7,8‐dihydro‐6H‐benzo[b ]pyrimido[5,4‐e ][1,4]thiazin‐2‐yl)morpholine ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h ). All the synthesized products were characterized and confirmed by their spectroscopic and microanalytical data.     

A concise,efficient and versatile synthesis of amino‐substituted benzo[b]pyrimido[5,4‐f]azepines: synthesis and spectroscopic characterization,together with the molecular and supramolecular structures of three products and one intermediate

A concise, efficient and versatile synthesis of amino‐substituted benzo[b]pyrimido[5,4‐f]azepines is described: starting from a 5‐allyl‐4,6‐dichloropyrimidine, the synthesis involves base‐catalysed aminolysis followed by intramolecular Friedel–Crafts cyclization. Four new amino‐substituted benzo[b]pyrimido[5,4‐f]azepines are reported, and all the products and reaction intermediates have been fully characterized by IR, ¹H and ¹³C NMR spectroscopy and mass spectrometry, and the molecular and supramolecular structures of three products and one intermediate have been determined. In each of N,2,6,11‐tetramethyl‐N‐phenyl‐6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepin‐4‐amine, C₂₂H₂₄N₅, (III), 4‐(1H‐benzo[d]imidazol‐1‐yl)‐6,11‐dimethyl‐6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepine, which crystallizes as a 0.374‐hydrate, C₂₁H₁₉N₅·0.374H₂O, (VIIIa), and 6,7,9,11‐tetramethyl‐4‐(5‐methyl‐1H‐benzo[d]imidazol‐1‐yl)‐6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepine, C₂₄H₂₅N₅, (VIIIc), the azepine ring adopts a boat conformation, but with a different configuration at the stereogenic centre in (VIIIc), as compared with (III) and (VIIIa). In the intermediate 5‐allyl‐6‐(1H‐benzo[d]imidazol‐1‐yl)‐N‐methyl‐N‐(4‐methylphenyl)pyrimidin‐4‐amine, C₂₂N₂₁N₅, (VIIb), the immediate precursor of 4‐(1H‐benzo[d]imidazol‐1‐yl)‐6,8,11‐trimethyl‐6,11‐dihydro‐5H‐benzo[b]pyrimido[5,4‐f]azepine, (VIIIb), the allyl group is disordered over two sets of atomic sites having occupancies of 0.688 (5) and 0.312 (5). The molecules of (III) are linked into chains by a C—H…π(pyrimidine) hydrogen bond, and those of (VIIb) are linked into complex sheets by three hydrogen bonds, one of the C—H…N type and two of C—H…π(arene) type. The molecules of the organic component in (VIIIa) are linked into a chain of rings by two C—H…π(arene) hydrogen bonds, and these chains are linked into sheets by the water components; a single weak C—H…N hydrogen bond links molecules of (VIIIc) into centrosymmetric R₂²(10) dimers. Comparisons are made with some related compounds.     

New Methods for the Synthesis of 3‐Amino‐6,7‐Dihydro‐5H‐Cyclopenta[c]Pyridine‐4‐Carbonitriles and Cyclopenta[d]Pyrazolo[3,4‐b]Pyridines via a Smiles‐type Rearrangement

By reaction with sodium ethoxide and as a function of their structures, 2‐[(1‐alkyl(aryl)‐4‐cyano‐6,7‐dihydro‐5H‐cyclopenta[c ]pyridin‐3‐yl)oxy]acetamides 11 gave 1‐amino‐5‐alkyl(aryl)‐7,8‐dihydro‐6H‐cyclopenta[d ]furo[2,3‐b ]pyridine‐2‐carboxamides 10 and/or 1‐alkyl(aryl)‐3‐amino‐6,7‐dihydro‐5H‐cyclopenta[c ]pyridine‐4‐carbonitriles 12 .     

Synthesis of Coumarin Substituted Triazolothiadiazine Derivatives via Ring Transformation Reaction

A novel ring transformation reaction for the synthesis of 3‐(3‐aryl‐7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazin‐6‐yl)‐2H‐chromen‐2‐ones has been described. Reaction of 3‐(2‐bromoacetyl)coumarins ( 1 ) with 5‐aryl‐1,3,4‐oxadiazole‐2‐thiol ( 2 ) gave ketones ( 4a–h ). The in situ formed ketones ( 4a–h ) were reacted with hydrazine hydrate to give 3‐(3‐aryl‐7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazin‐6‐yl)‐2H‐chromen‐2‐ones ( 3a–h ) and not 5 or 6 . The compounds ( 3a–h ) can also be prepared by the reaction of 3‐(2‐bromoacetyl)coumarins ( 1 ) with 5‐aryl‐1,3,4‐oxadiazole‐2‐thiol ( 2 ) in anhydrous ethanol to give corresponding 3‐(2‐(5‐aryl‐1,3,4‐oxadiazol‐2‐ylthio)acetyl)‐2H‐chromen‐2‐ones ( 4a–h ). These on reaction with hydrazine hydrate in acetic acid gave corresponding 3‐(3‐aryl‐7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazin‐6‐yl)‐2H‐chromen‐2‐ones ( 3a–h ).     

Synthesis of novel coumarin and benzocoumarin derivatives and their biological and photophysical studies

Several derivatives of coumarin‐3N‐carboxamides ( 3‐21 ) have been prepared via the reaction of the coumarin‐3‐carbonyl chloride ( 1 ) with a number of nucleophiles. Novel double‐headed coumarin‐3N‐carboxamides ( 26‐33 ) were also produced using the same method. The Pechmann‐Duisberg reaction was applied to prepare new benzo[f]‐ benzo[h]coumarins and 4‐(chloromethyl)‐pyrano[3,2‐c]coumarin‐2‐one ( 36‐42 ). The reaction of 1‐chloromethylbenzo[f]coumarins ( 36 ) with cyanide anion under different reaction conditions was also investigated in order to assess its suitability for nucleophilic substitution reactions as well as ring transformation products ( 43‐49 ). Synthesis of 1‐((benzo[d]thiazol‐2‐yl)methyl)‐9‐hydroxybenzo[ f ]coumarin ( 50 ) represented the first example of methylene bridge‐head heterocyclecontaining benzo[f]coumarin. Some of the newly prepared coumarins exhibited anti‐bacterial activity against Gram Positive and Gram negative bacteria. Compound 36d was found to be active against all the screened bacteria. Photophysical studies were performed on selected fluorescent benzo[f]‐ and benzo[h]coumarin and the quantum yields were also calculated. All new compounds were characterized by IR, MS, ¹H and ¹³C NMR, as well as elemental analysis.     

Mannich Reaction as a New Route for the Synthesis of Tetrahydro Pyrimido Benzimidazolyl Coumarins

Condensation of coumarin‐4‐acetic acids ( 1 ) with ortho‐phenylenediamine ( 2 ) in anhydrous phosphoric acid afforded 4‐((1H‐benzo[d]imidazol‐2‐yl)methyl)‐2H‐chromen‐2‐ones ( 3 ). Attempted Mannich reaction of 3 with formalin and primary amines resulted in 4‐(2‐phenyl‐1,2,3,4‐tetrahydrobenzo[4,5]imidazo[1,2‐c]pyrimidin‐4‐yl)‐2H‐chromen‐2‐ones ( 6 ). The structures of synthesized compounds were elucidated by analyses including 2D HETCOR and DEPT experiments. Synthesized compounds have been subjected for anti‐inflammatory activity. Compound 6j exhibited promising anti‐inflammatory activity.     

Synthesis of new 5‐substitutedbenzo[b]thiophene derivatives

Previous works of our group have dealt with the synthesis of 1‐(aryl)‐3‐[4‐(aryl)piperazin‐1‐yl]propane derivatives in the search for new and efficient antidepressants with a dual mode of action: serotonin reuptake inhibition and 5‐HT_1A receptor afinity [1‐4]. From these studies we concluded that the 3‐[4‐(aryl)piperazin‐1‐yl]‐1‐(benzo[b]thiophen‐3‐yl)propane derivatives led to the best results. The continuation of this research project required the preparation of some new 3‐acyl‐5‐substituted benzo[b]thiophenes with a wide variety of substituents at the 5 position, ranging from nitro to hydroxyl derivatives. To obtain these derivatives we acylated the corresponding 5‐substituted benzo[b]thiophenes when it was possible.     

A Convenient Synthesis of 2H‐Pyran‐2‐ones,Fused Pyran‐2‐ones,and Pyridones Bearing a Thiazole Moiety

The versatile enaminonitrile, 2‐cyano‐3‐(dimethylamino)‐N‐(4‐phenylthiazol‐2‐yl)‐acrylamide ( 2 ), reacts with some C,O‐binucleophiles (acetylacetone and dimedone) in refluxing acetic acid to afford the pyranone 4 , the chromene 6 derivatives, and with C,N‐binucleophiles (2‐(benzothiazol‐2‐yl)acetonitrile and 2‐(1H‐benzimidazol‐2‐yl)acetonitrile) to afford the respective 1H‐pyrido[2,1‐b]benzothiazole 8 and pyrido[1,2‐a]benzimidazole 10 derivatives. Similar treatment of 2 with phenol, resorcinol, α‐naphthol and β‐naphthol in boiling acetic acid gave the coumarin derivatives 12 , 14 , 16 , and 18 , respectively. The utility of enaminonitrile 2 for the synthesis of 6H‐pyrano[3,2‐d]isoxazole 20 , pyrano[2,3‐c]pyrazole 22 , and pyrano[2,3‐d]pyrimidine 24 derivatives was also explored via its reaction with 3‐phenylisoxazol‐5(4H)‐one, 3‐methyl‐1‐phenyl‐1H‐pyrazol‐5(4H)‐one, and barbituric acid, respectively. The mechanistic aspects for the formation of the new compounds were also discussed.     

A convenient one‐pot synthesis of new 3‐(4‐aryl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2‐yl)‐2H‐chromen‐2‐ones

Anhydrous zinc bromide catalysed reactions of arylidine‐3‐acetyl coumarins ( 1a‐c ) and 5,6‐benzoanalogs of arylidine 3‐acetyl coumarins ( 4a,4b ) with 1,3‐cyclohexanedione gives ‐(4‐aryl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2yl)‐2H‐chromen‐2‐ones ( 3a, 3c ) and 5,6‐benzoanalogs of 3‐(4‐aryl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2yl)‐2H‐chromen‐2‐one ( 5a,5b ). Under similar conditions arylidine‐3‐acetylcoumarins ( 1a, 1b,1d, 1e, 1f ) and 5,6‐benzoanalog of arylidine 3‐acetyl coumarin ( 4b ) react with 5,5‐dimethyl‐1,3‐cyclohexanedione (dimedone) yielding 3‐(4‐aryl‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2‐yl)‐2H‐chromen‐2‐ones ( 3d‐3h ) and the 5,6‐benzoanalog of 3.(4‐aryl‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐tetrahydro‐4H‐chromen‐2‐yl)‐2H‐chromen‐2‐one ( 5c ).     

First synthesis of 2‐(2,4,4‐trimethyl‐3,4‐dihydro‐2H‐benzo[h]chromen‐2‐yl)‐1‐naphthol and 3‐(2,4,4‐trimethyl‐3,4‐dihydro‐2H‐benzo[g]chromen‐2‐yl)‐2‐naphthol from 1‐ and 2‐naphthol derivatives

Two new structurally isomeric, 2‐(2,4,4‐trimethyl‐3,4‐dihydro‐2H‐benzo[h]chromen‐2‐yl)‐1‐naphthol ( 1 ) and 3‐(2,4,4‐trimethyl‐3,4‐dihydro‐2H‐benzo[g]chromen‐2‐yl)‐2‐naphthol ( 3 ) have been synthesized from 2‐acetyl‐1‐naphthol and ethyl‐3‐hydroxy‐2‐naphthoate, respectively, involving Grignard reaction, dehydration of the corresponding tertiary alcohols, and hetero Diels–Alder dimerization. The two benzochromenes ( 1 and 3 ) have been fully characterized by IR, NMR, and HRESIMS data. Their structures are further supported by crystallography of their corresponding acetates ( 2 and 4 ). J. Heterocyclic Chem., (2011).     

A concise and efficient synthesis of amino‐substituted (1H‐benzo[d]imidazol‐1‐yl)pyrimidine hybrids: synthetic sequence and the molecular and supramolecular structures of six examples

A concise and efficient synthesis of a series of amino‐substituted benzimidazole–pyrimidine hybrids has been developed, starting from the readily available N⁴‐(2‐aminophenyl)‐6‐methoxy‐5‐nitrosopyrimidine‐2,4‐diamine. In each of N⁵‐benzyl‐6‐methoxy‐4‐(2‐phenyl‐1H‐benzo[d]imidazol‐1‐yl)pyrimidine‐2,5‐diamine, C₂₅H₂₂N₆O, (I), 6‐methoxy‐N⁵‐(4‐methoxybenzyl)‐4‐[2‐(4‐methoxyphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, C₂₇H₂₆N₆O₃, (III), 6‐methoxy‐N⁵‐(4‐nitrobenzyl)‐4‐[2‐(4‐nitrophenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, C₂₅H₂₀N₈O₅, (IV), the molecules are linked into three‐dimensional framework structures, using different combinations of N—H…N, N—H…O, C—H…O, C—H…N and C—H…π hydrogen bonds in each case. Oxidative cleavage of 6‐methoxy‐N⁵‐(4‐methylbenzyl)‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, (II), with diiodine gave 6‐methoxy‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidine‐2,5‐diamine, which crystallized as a monohydrate, C₁₉H₁₈N₆O·H₂O, (V), and reaction of (V) with trifluoroacetic acid gave two isomeric products, namely N‐{5‐amino‐6‐methoxy‐6‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidin‐2‐yl}‐2,2,2‐trifluoroacetamide, which crystallized as an ethyl acetate monosolvate, C₂₁H₁₇F₃N₆O₂·C₄H₈O₂, (VI), and N‐{2‐amino‐6‐methoxy‐4‐[2‐(4‐methylphenyl)‐1H‐benzo[d]imidazol‐1‐yl]pyrimidin‐5‐yl}‐2,2,2‐trifluoroacetamide, which crystallized as a methanol monosolvate, C₂₁H₁₇F₃N₆O₂·CH₄O, (VIIa). For each of (V), (VI) and (VIIa), the supramolecular assembly is two‐dimensional, based on different combinations of O—H…N, N—H…O, N—H…N, C—H…O and C—H…π hydrogen bonds in each case. Comparisons are made with some related structures.     

Green One‐Pot Solvent‐Free Synthesis of Pyrazolo[1,5‐a]pyrimidines,Azolo[3,4‐d]pyridiazines,and Thieno[2,3‐b]pyridines Containing Triazole Moiety

Synthesis of pyrazolo[1,5‐a]pyrimidines, [1,2,4]triazolo[1,5‐a]pyrimidine, 8,10‐dimethyl‐2‐(5‐methyl‐1‐phenyl‐4,5‐dihydro‐1H‐1,2,3‐triazol‐4‐yl)pyrido[2′,3′:3,4]‐pyrazolo[1,5‐a]pyrimidine, benzo[4,5]imidazo[1,2‐a]pyrimidine via heterocyclic amines, and sodium 3‐hydroxy‐1‐(5‐methyl‐1‐phenyl‐1H‐1,2,3‐triazole‐4‐yl)prop‐2‐en‐1‐one were carried out. Also, synthesis of isoxazoles, and pyrazoles from sodium 3‐hydroxy‐1‐(5‐methyl‐1‐phenyl‐1H‐1,2,3‐triazole‐4‐yl)prop‐2‐en‐1‐one and hydroxymoyl chlorides and hydrazonoyl halides, respectively, were made. Analogously, (1,2,3‐triazol‐4‐yl)thieno[2,3‐b]pyridine derivatives were obtained from sodium 3‐hydroxy‐1‐(5‐methyl‐1‐phenyl‐1H‐1,2,3‐ triazole‐4‐yl)prop‐2‐en‐1‐one and cyanothioacetamide followed by its reacting with active methylene compounds. In addition to full characterization of all synthesized compounds, they were tested to evaluate their antimicrobial activities, and some compounds showed competitive activities to those of tetracycline, the typical antibacterial drug, and clotrimazole, the typical antifungal drug.     

Michael-Addition Reaction of Malononitrile with α,β-Unsaturated Cycloketones Catalyzed by KF／Al2O3

A series of KF/Al2O3 catalyzed Michael-addition reactions between malononitrile and α,β-unsaturated cycloketones in DMF solution were studied. At room temperature, 2-cyano-3-aryl-3-(1,2,3,4-tetrahydronaphthalen-1-one-2-yl) propionitrile derivatives were synthesized by the reaction between 2-arylmethylidene-1,2,3,4-tetra-hydronaphthalen-1-one and malononitrile. However, if the temperature was increased to 80℃, 2-amino-3-cyano-4-aryl-4H-benzo[h]chromene derivatives were obtained in high yields. When the α,β-unsaturated ketones were replaced by 2,6-biarylmethylidenecyclohexanone or 2,5-biarylmethylidenecyclopentanone, another series of 2-amino-3-cyano-4H-pyran derivatives was isolated successfully. The structures of the products were confirmed by X-ray diffraction analysis.     

An Innovative Protocol for the Synthesis of 3‐(Pyridin‐2‐yl)‐5‐sec‐aminobiphenyl‐4‐carbonitriles and 9,10‐Dihydro‐3‐(pyridine‐2‐yl)‐1‐sec‐aminophenanthrene‐2‐carbonitriles

Herein, we present an innovative, novel, and highly convenient protocol for the synthesis of 3‐(pyridin‐2‐yl)‐5‐sec‐aminobiphenyl‐4‐carbonitriles ( 6a , 6b , 6c , 6d , 6e , 6f , 6g ) and 9,10‐dihydro‐3‐(pyridine‐2‐yl)‐1‐sec‐aminophenanthrene‐2‐carbonitriles ( 10a , 10b , 10c , 10d , 10e ), which have been delineated from the reaction of 4‐sec‐amino‐2‐oxo‐6‐aryl‐2H‐pyran‐3‐carbonitrile ( 4a , 4b , 4c , 4d , 4e , 4f , 4g ) and 4‐sec‐amino‐2‐oxo‐5,6‐dihydro‐2H‐benzo[h]chromene‐3‐carbonitriles ( 9a , 9b , 9c , 9d , 9e ) with 2‐acetylpyridine ( 5 ) through the ring transformation reaction by using KOH/DMF system at RT. The salient feature of this procedure is to provide a transition metal‐free route for the synthesis of asymmetrical 1,3‐teraryls like 3‐(pyridin‐2‐yl)‐5‐sec‐aminobiphenyl‐4‐carbonitriles ( 6a , 6b , 6c , 6d , 6e , 6f , 6g ) and 9,10‐dihydro‐3‐(pyridine‐2‐yl)‐1‐sec‐aminophenanthrene‐2‐carbonitriles ( 10a , 10b , 10c , 10d , 10e ). The novelty of the reaction lies in the creation of an aromatic ring from 2H‐pyran‐2‐ones and 2H‐benzo[h]chromene‐3‐carbonitriles via two‐carbon insertion from 2‐acetylpyridine ( 5 ) used as a source of carbanion.     

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.     

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 of Some New Pyridine and Pyrimidine Derivatives Containing Benzothiazole Moiety

A variety of pyridine and pyrimidine rings incorporating benzothiazole moiety were synthesized by reaction of 1‐(2‐benzothiazolyl)‐1‐cyano‐3‐chloroacetone ( 1 ) with 2‐pyridone, 2‐thioxopyridine, thiouracil, and 2‐thioxopyrimidine derivatives to give compounds 7,9‐dimethylfuro[2,3‐b:4,5‐b′]dipyridin‐4‐ol 5 , 4, 6‐diphenylthieno[2,3‐b]pyridin‐2‐yl 9 , 2‐(benzo[d]thiazol‐2‐yl)‐2‐(7‐substituted‐5‐oxo‐5H‐thiazolo[3,2‐a]pyrimidin‐3‐yl)acetonitriles 12a and 12b , pyrimido[2,1‐b][1,3]thiazepine‐3‐carboxamide 15 , and benzo[4,5]thiazolo[3,2‐b]pyridazine‐3‐one 20 , respectively.