New synthesis and reactivity of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one with binucleophilic amines

3‐(Bromoacetyl)‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one was synthesized by the reaction of dehydroacetic acid (DHAA) with bromine in glacial acetic acid. Novel heterocyclic products were synthesized from the reaction of bromo‐DHAA with alkanediamines, phenylhydrazines, ortho‐phenylenediamines, and ortho‐aminobenzenethiol. The obtained new products 3‐(2‐N‐substituted‐acetyl)‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐ones, 4‐hydroxy‐3‐[1‐hydroxy‐2‐(2‐phenylhydrazinyl)vinyl]‐6‐methyl‐2H‐pyran‐2‐one, 1‐(2,4‐dinitrophenyl)‐7‐methyl‐2,3‐dihydro‐1H‐pyrano[4,3‐c]pyridazine‐4,5‐dione, 3‐(3,4‐dihydroquinoxalin‐2‐yl)‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one/3‐(3,4‐dihydroquinoxalin‐2‐yl)‐6‐methyl‐2H‐pyran‐2,4(3H)‐dione, 6‐methyl‐3‐(3,4‐dihydroquinoxalin‐2‐yl)‐2H‐pyran‐2,4(3H)‐dione, and (E)‐3‐(2H‐benzo[b][1,4]thiazin‐3(4H)‐ylidene)‐6‐methyl‐2H‐pyran‐2,4(3H)‐dione were fully characterized by IR, ¹H and ¹³C NMR, and mass spectra. J. Heterocyclic Chem., 2011.     

Attempted synthesis of ethyl 3,4‐dihydro‐2H‐1,4‐benzoxazine‐3‐carboxylate and 3‐acetate derivatives

Ethyl 3,4‐dihydro‐2H‐1,4‐benzoxazine‐3‐carboxylate derivatives 2 were obtained and isolated in low yields from the condensation of 2‐aminophenol and ethyl 2,3‐dibromopropanoate. They can be obtained by hydrogenation of ethyl 2H‐1,4‐benzoxazine‐3‐carboxylate in satisfactory yield. Using 2‐iminophenol did not direct the condensation with ethyl 2,3‐dibromopropanoate towards 2 but was fruitfull for the preparation of ethyl 2‐(4‐benzyl‐3,4‐dihydro‐2H‐1,4‐benzoxazin‐3‐yl)acetate from ethyl bromocrotonate.     

A Novel and Efficient Synthesis of 3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐ones (=3‐[(4,5‐Dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐1‐benzopyran‐2‐ones)

An efficient one‐pot synthesis of 3‐[(4,5‐dihydro‐1H‐pyrrol‐3‐yl)carbonyl]‐2H‐chromen‐2‐one (=3‐[(4,5‐dihydro‐1H‐pyrrol‐3yl)carbonyl]‐2H‐1‐benzopyran‐2‐one) derivatives 4 by a four‐component reaction of a salicylaldehyde 1 , 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one, a benzylamine 2 , and a diaroylacetylene (=1,4‐diarylbut‐2‐yne‐1,4‐dione) 3 in EtOH is reported. This new protocol has the advantages of high yields (Table), and convenient operation. The structures of these coumarin (=2H‐1‐benzopyran‐2‐one) derivatives, which are important compounds in organic chemistry, were confirmed spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme 2).     

Synthesis,Cytotoxicity and Antibacterial Studies of Novel Symmetrically and Nonsymmetrically 4‐(Methoxycarbonyl)benzyl‐Substituted N‐Heterocyclic Carbene–Silver Acetate Complexes

From the reaction of 1H‐imidazole ( 1a ), 4,5‐dichloro‐1H‐imidazole ( 1b ), 1H‐benzimidazole ( 1c ), 1‐methyl‐1H‐imidazole ( 1d ), and 1‐methyl‐1H‐benzimidazole ( 1f ) with methyl 4‐(bromomethyl)benzoate ( 2 ), symmetrically and nonsymmetrically 4‐(methoxycarbonyl)benzyl‐substituted N‐heterocyclic carbene (NHC) precursors, 3a – 3f , were synthesized. These NHC precursors were then reacted with silver(I) acetate (AgOAc) to yield the NHC–silver acetate complexes (acetato‐κO){1,3‐bis[4‐(methoxycarbonyl)benzyl]imidazol‐2‐ylidene}silver ( 4a ), (acetato‐κO){4,5‐dichloro‐1,3‐bis[4‐(methoxycarbonyl)benzyl]‐2,3‐dihydro‐1H‐imidazol‐2‐yl}silver ( 4b ), (acetato‐κO){1,3‐bis[4‐(methoxycarbonyl)benzyl]‐2,3‐dihydro‐1H‐benzimidazol‐2‐yl}silver ( 4c ), (acetato‐κO){1‐[4‐(methoxycarbonyl)benzyl]‐3‐methyl‐2,3‐dihydro‐1H‐imidazol‐2‐yl}silver ( 4d ), (acetato‐κO){4,5‐dichloro‐1‐[4‐(methoxycarbonyl)benzyl]‐3‐methyl‐2,3‐dihydro‐1H‐imidazol‐2‐yl}silver ( 4e ), and (acetato‐κO){1‐[4‐(methoxycarbonyl)benzyl]‐3‐methyl‐2,3‐dihydro‐1H‐benzimidazol‐2‐yl}silver ( 4f ), respectively. The three NHC–AgOAc complexes 4a, 4c , and 4d were characterized by single‐crystal X‐ray diffraction. All compounds studied in this work were preliminarily screened for their antimicrobial activities in vitro against Gram‐positive bacteria Staphylococcus aureus, and Gram‐negative bacteria Escherichia coli using the qualitative disk‐diffusion method. All NHC–AgOAc complexes exhibited weak‐to‐medium antibacterial activity with areas of clearance ranging from 4 to 7 mm at the highest amount used, while the NHC precursors showed significantly lower activity. In addition, NHC–AgOAc complexes 4a and 4b , and 4d – 4f exhibited in preliminary cytotoxicity tests on the human renal‐cancer cell line Caki‐1 medium‐to‐high cytotoxicities with IC₅₀ values ranging from 3.3±0.4 to 68.3±1 μM .     

Reactions of 3‐benzylindole‐2‐carbohydrazides: Synthesis of new 10‐Benzyl‐1,2‐dihydro‐1‐oxo‐1,2,4‐triazino[4,5‐a]indoles and 3‐Benzyl‐2‐(1,3,4‐oxadiazol‐2‐yl)indoles

3‐Benzylindole‐2‐carbohydrazides (4) on reaction with triethylorthoformate in a polar solvent like DMF yielded only 10‐benzyl‐1,2‐dihydro‐1‐oxo‐1,2,4‐triazino[4,5‐a]indoles (5) while (4) on reaction with triethylorthoacetate in DMF yielded both 10‐benzyl‐4‐methyl‐1,2‐dihydro‐1‐oxo‐1,2,4‐triazino[4,5‐a]indoles (5) and 3‐benzyl‐2‐(5‐methyl‐1,3,4‐oxadiazol‐2‐yl)indoles (6) instead of only the triazinoindoles as expected. The oxadiazolylindoles (6) were also synthesized by refluxing (4) with excess of orthoesters. The structures of the compounds formed were characterized by their analytical and spectral data.     

An Efficient Synthesis of N‐Substituted‐3‐aryl‐3‐(4‐hydroxy‐6‐methyl‐2‐oxo‐2H‐pyran‐3‐yl)propanamides by Four‐Component Reaction in Aqueous Medium

A mild and efficient synthesis of N‐substituted‐3‐aryl‐3‐(4‐hydroxy‐6‐methyl‐2‐oxo‐2H‐pyran‐3‐yl)propanamides via four‐component reaction of an aldehyde, amine, Meldrum's acid, and 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one in the presence of benzyltriethylammonium chloride (TEBAC) in aqueous medium is described. This method has the advantages of accessible starting materials, good yields, mild reaction conditions, and begin environmentally friendly.     

Synthesis and reactivity of 6‐methyl‐4H‐furo[3,2c]pyran‐3,4‐dione

An efficient synthesis of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one by bromination of dehydroacetic acid in glacial acetic acid is described. Novel 4‐hydroxy‐6‐methyl‐3‐(2‐substituted‐thiazol‐4‐yl)‐2H‐pyran‐2‐ones have been prepared from the reaction of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one with thioamides, thiourea, and diphenylthiocarbazone. The condensation reaction of 6‐methyl‐4H‐furo[3,2c]pyran‐3,4‐dione, obtained from the reaction of 3‐bromoacetyl‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one with aliphatic amines, with benzaldehydes and acetophenones led to novel 2‐arylidene‐6‐methyl‐2H‐furo[3,2‐c]pyran‐3,4‐diones and 6‐(2‐arylprop‐1‐enyl)‐2H‐furo[3,2‐c]pyran‐3,4‐diones. The structure of all compounds was established by elemental analysis, IR, NMR, and mass spectra. J. Heterocyclic Chem., 2011.     

Strategy to Construct Stair‐Shaped Partially Reduced Naphtho[1,2‐b]pyrano[2,3‐d]oxepines and Dinaphtho[1,2‐b,d]oxepines

A concise and efficient base‐induced synthesis of stair‐shaped, 4‐methylthio‐2‐oxo‐5,6‐dihydro‐2H‐naphtho[1,2‐b]pyran[2,3‐d]oxepine‐3‐carbonitriles ( 3 ) has been delineated by the reaction of 3,4‐dihydronaphtho[1,2‐b]oxepin‐5(2H)‐one ( 1 ) and methyl 2‐cyano‐3,3‐dimethylthioacrylate in DMSO using powdered KOH as a base at room temperature. Amination of 3 has been achieved by reaction with secondary amine in ethanol at reflux temperature to yield 4‐sec‐amino‐2‐oxo‐5,6‐dihydro‐2H‐naphtho[1,2‐b]pyran[2,3‐d]oxepine‐3‐carbonitriles ( 4 ). Reaction of 3 with aryl methyl ketone ( 5 ) in DMSO at room temperature using powdered KOH as a base produced stair‐shaped 5‐aryl‐7,8‐dihydro‐1,4‐dioxa‐2,3‐dioxodinaphtho[1,2‐b,d]oxepine ( 6 ) in good yields. However, reaction of 6‐aryl‐2H‐pyran‐2‐one‐3‐carbonitrile ( 8 ) with 3,4‐dihydronaphtho[1,2‐b]oxepin‐5(2H)‐one ( 1 ) did not give similar product, but in lieu 4‐aryl‐5,6‐dihydronaphtho[1,2‐b]oxepino[4,5‐b]pyran‐2‐ylidene)acetonitrile ( 9 ) was isolated and characterized.     

Synthesis of Novel 3‐(3‐(5‐Methylisoxazol‐3‐yl)‐7H‐[1,2,4]Triazolo [3,4‐b][1,3,4]Thiadiazin‐6‐yl)‐2H‐Chromen‐2‐Ones

A novel series of coumarin substituted triazolo‐thiadiazine derivatives were designed and synthesized by using 5‐methyl isoxazole‐3‐carboxylic acid ( 1 ), thiocarbohydrazide ( 2 ), and various substituted 3‐(2‐bromo acetyl) coumarins ( 4a , 4b , 4c , 4e , 4d , 4f , 4g , 4h , 4i , 4j ). Fusion of 5‐methyl isoxazole‐3‐carboxylic acid with thiocarbohydrazide resulted in the formation of the intermediate 4‐amino‐5‐(5‐methylisoxazol‐3‐yl)‐4H‐1,2,4‐triazole‐3‐thiol ( 3 ). This intermediate on further reaction with substituted 3‐(2‐bromo acetyl) coumarins under simple reaction conditions formed the title products 3‐(3‐(5‐methylisoxazol‐3‐yl)‐7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazin‐6‐yl‐2H‐chromen‐2‐ones ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j ) in good to excellent yields. All the synthesized compounds were well characterized by physical, analytical, and spectroscopic techniques.     

A Convenient Synthetic Route of Diethyl (4‐Oxo‐chromeno[2,3‐d]pyrimidin‐2(5)‐yl)phosphonates

Novel diethyl (4‐oxo‐3,4‐dihydro‐2H‐chromeno[2,3‐d]pyrimidin‐2‐yl)phosphonate as two enantiomers and diethyl (4‐oxo‐1,5‐dihydro‐4H‐chromeno[2,3‐d]pyrimidin‐5‐yl) phosphonate were obtained in easy procedure via reaction of 2‐imino‐2H‐chromene‐3‐carboxamide, dimethylformamide dimethyl‐acetal, and diethyl phosphite in a simple one pot. Possible reaction mechanisms were proposed. The structures of the obtained products were confirmed by elemental analyses and spectral tools.     

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 and Antiplatelet‐Activity Evaluation of α‐Methylidene‐γ‐butyrolactones Bearing 3,4‐Dihydroquinolin‐2(1H)‐one Moieties

In continuation of our search for potent antiplatelet agents, we have synthesized and evaluated several α‐methylidene‐γ‐butyrolactones bearing 3,4‐dihydroquinolin‐2(1H)‐one moieties. O‐Alkylation of 3,4‐dihydro‐8‐hydroxyquinolin‐2(1H)‐one ( 1 ) with chloroacetone under basic conditions afforded 3,4‐dihydro‐8‐(2‐oxopropoxy)quinolin‐2(1H)‐one ( 2a ) and tricyclic 2,3,6,7‐tetrahydro‐3‐hydroxy‐3‐methyl‐5H‐pyrido[1,2,3‐de][1,4]benzoxazin‐5‐one ( 3a ) in a ratio of 1 : 2.84. Their Reformatsky‐type condensation with ethyl 2‐(bromomethyl)prop‐2‐enoate furnished 3,4‐dihydro‐8‐[(2,3,4,5‐tetrahydro‐2‐methyl‐4‐methylidene‐5‐oxofuran‐2‐yl)methoxy]quinolin‐2(1H)‐one ( 4a ), which shows antiplatelet activity, in 70% yield. Its 2′‐Ph derivatives, and 6‐ and 7‐substituted analogs were also obtained from the corresponding 3,4‐dihydroquinolin‐2(1H)‐ones via alkylation and the Reformatsky‐type condensation. Of these compounds, 3,4‐dihydro‐7‐[(2,3,4,5‐tetrahydro‐4‐methylidene‐5‐oxo‐2‐phenylfuran‐2‐yl)methoxy]quinolin‐2(1H)‐one ( 10b ) was the most active against arachidonic acid (AA) induced platelet aggregation with an IC₅₀ of 0.23 μM . For the inhibition of platelet‐activating factor (PAF) induced aggregation, 6‐{[2‐(4‐fluorophenyl)‐2,3,4,5‐tetrahydro‐4‐methylidene‐5‐oxofuran‐2‐yl]methoxy}‐3,4‐dihydroquinolin‐2(1H)‐one ( 9c ) was the most potent with an IC₅₀ value of 1.83 μM .     

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).     

Facile Synthesis of N‐(Benzyl‐1H‐1,2,3‐Triazol‐5‐yl) Methyl)‐4‐(6‐Methoxybenzo [d] Thiazol‐2‐yl)‐2‐Nitrobenzamides via Click Chemistry

A series of novel N‐((l‐benzyl‐lH‐l,2,3‐triazol‐5‐yl) methyl)‐4‐(6‐methoxy benzo[d ]thiazol‐2‐yl)‐2‐nitrobenzamide derivatives were prepared from 4‐(6‐methoxybenzo[d ]thiazol‐2‐yl)‐2‐nitro‐N‐(prop‐2‐ynyl) benzamide with benzyl azides by using click reaction (copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction) in the presence of CuSO₄.5H₂O and sodium ascaorbate. All the newly synthesized compounds were evaluated further in vitro antimicrobial activity against Gram‐positive bacteria (Staphylococcus aureus and Bacillus subtillis ), Gram‐negative bacteria (Echerichia coli and Pseudomonas aeuroginosa ), and fungi (Aspergillus niger and Aspergillusfumigatus ) strains. The new compounds were characterized based on spectroscopic evidence. Among them compounds 10a , 10h , and 10i were showed promising activity when compared with standard drugs Ciprofloxacin and Miconazole.     

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.     

Facile Synthesis of Novel 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one Derivatives as Potential Anticancer Agents

A series of 3‐(4‐phenylisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 6a – l ) derivatives has been efficiently synthesized by straightforward sequential reactions. Tandem Vilsmeier Hack reaction/cyclization/bromination/Suzuki cross‐coupling reactions were successfully applied to the preparation of title compounds in good‐to‐high yields. In the synthetic sequences, 3‐chloro‐3‐(2‐oxo‐2H‐chromen‐3‐yl)acrylaldehydes ( 2 ) were found to react with ammonium thiocyanate to yield the corresponding 3‐(isothiazol‐5‐yl)‐2H‐chromen‐2‐ones ( 3 ). These derivatives were brominated with N‐bromo succinamide to yield the corresponding regioselective 3‐(4‐bromoisothiazol‐5‐yl)‐2H‐chromen‐2‐one ( 4 ). Finally, compound 4 was treated with various phenyl/pyrazole/7H –pyrrolo[2,3‐d]pyrimidinyl boronic acids 5a – l in the presence of K₂CO₃ and Pd catalyst in dimethylformamide to yield the corresponding title derivatives 6a – l . All the synthesized compounds were characterized by analytical and spectral studies. All the final compounds were screened against different cancer cell lines (A549, PC3, SKOV3, and B16F10), and among these compounds, 6b , 6g , 6h , and 6l displayed moderate cytotoxic activity against the tested cell lines.     

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.     

Regioselective Synthesis and Antibacterial Activity Studies of 1,2,3‐Triazol‐4‐YL]‐4‐methyl‐2H‐chromen‐2‐ones

Synthesis, spectral analysis, and antibacterial activity of new coumarin derivatives are described in this paper. Twelve new coumarin derivatives were synthesized in moderate to good yields by the react with 4‐methyl‐6‐(prop‐2‐ynyloxy)‐2H‐chromen‐2‐one ( 3a – c ) and ethyl azide ( 4a – l ) and done by the click reaction to obtained 6‐[(l‐ethyl‐lH‐l,2,3‐triazol‐4‐yl)methoxy]‐4‐methyl‐2H‐chromen‐2‐ones ( 5a – l ). The structures of all the newly synthesized molecules were assigned by elemental analysis and spectral data. The synthesized compounds were screened for their antibacterial activities strains using Cup plate method.     

Synthesis and Antibacterial Activity of Novel (4‐Fluorophenyl)(4‐(naphthalen‐2‐yl)‐6‐aryl‐2‐thioxo‐2,3‐dihydropyrimidin‐1(6H)‐yl)methanone Derivatives

A novel series of (4‐fluorophenyl)(4‐(naphthalen‐2‐yl)‐6‐aryl‐2‐thioxo‐2,3‐dihydropyrimidin‐1(6H)‐yl)methanone derivatives were synthesized from reaction of 6‐(naphthalen‐2‐yl)‐4‐aryl‐3,4‐dihydropyrimidine‐2(1H)‐thiones with 4‐fluorobenzoylchloride in dichloromethane in the presence of triethylamine. The synthesized compounds were screened for antibacterial activity against Gram positive bacteria, namely, Staphylococcus aureus ATCC25923 and Listeria monocytogenes MTCC657, and Gram negative bacteria, namely, Escherichia coli ATCC25922 and Klebsiella pneumoniae ATCC700603, respectively. Some of the tested compounds showed significant antimicrobial activity.     

Synthesis of 2‐amino‐4‐(2‐ethoxybenzo[d][1,3]dioxol‐5‐yl)‐4H‐pyran‐3‐Carbonitrile Derivatives and Their Biological Evaluation

A new class of substituted 2‐amino‐4‐(2‐ethoxybenzo[d][1,3]dioxol‐5‐yl)‐4H‐pyran‐3‐carbonitrile derivatives catalyzed by Imidazole under mild reaction conditions has been developed. A variety of functionalized 2‐amino‐4‐(2‐ethoxybenzo[d][1,3]dioxol‐5‐yl)‐4H‐pyran‐3‐carbonitrile scaffolds were assembled in high yields by this catalytic protocol. The newly synthesized compounds have been characterized by IR, ¹H NMR, ¹³C NMR, and mass spectral data. The compounds were then evaluated for antimicrobial activities.