Synthesis and Hypolipidemic Activity of New 6,6‐Disubstituted 3‐R‐6,7‐Dihydro‐2H‐[1,2,4]triazino[2,3‐c]quinazolin‐2‐Ones

Presented article describes the synthesis and hypolipidemic activity of previously unknown 6,6‐disubstituted 3‐R‐6,7‐dihydro‐2H‐[1,2,4]triazino[2,3‐c]quinazolin‐2‐ones. It was shown, that interaction of 6‐R‐3‐(2‐aminophenyl)‐1,2,4‐triazin‐5(2Н)‐оnes with methylalkylketones in acetic acid resulted the single product, namely, the desired tricyclic derivatives. At the same time, after refluxing of 6‐R‐3‐(2‐aminophenyl)‐1,2,4‐triazin‐5(2Н)‐оnes with methylarylketones in acetic acid the mixture of target compound and insignificant amount of corresponding 3‐substituted 6‐methyl‐2H‐[1,2,4]triazino[2,3‐c]quinazolin‐2‐ones were isolated. The mechanism of above‐mentioned mixture formation was discussed. The structures of all synthesized compounds were proven using the appropriate physicochemical methods. The compounds with promising lipid‐lowering activity were identified and the «structure — hypolipidemic activity» correlations were discussed.     

Simple synthesis of 2‐amino‐4‐(het)aryl‐4,6‐dihydro‐1(3)(11)H‐[1,3,5]triazino[2,1‐b]quinazolin‐6‐ones

The 2‐amino‐4‐(het)aryl‐4,6‐dihydro‐1(3)(11)H‐[1,3,5]triazino[2,1‐b]quinazolin‐6‐ones were prepared readily by cyclocondensation of anthranilic acid derived 4‐oxo‐3,4‐dihydroquinazolinyl‐2‐guanidine with a variety of aldehydes. The structures of the compounds were confirmed by nmr spectroscopy, including 2D NOESY experiments.     

Interaction of 4‐Oxo‐4H‐pyrazolo[5,1‐c][1,2,4]triazin‐1‐ides with Grignard Reagents

Reactions of magnesium 3‐tert‐butyl‐8‐R‐4‐oxo‐4H‐pyrazolo[5,1‐c][1,2,4]triazin‐1‐ides (R = CN, CO₂Et) with AlkMgBr led to nucleophilic additions to either side chain or triazine core, with selectivity being dependent on the nature of substituents, as well as on the solvents used. Previously inaccessible C⁸‐functionalized and C⁴‐functionalized pyrazolo[5,1‐c][1,2,4]triazines and 3‐tert‐butyl‐3‐ethyl‐4‐oxo‐1,2,3,4‐tetrahydropyrazolo[5,1‐c][1,2,4]triazine were synthesized, and their reactivity and spectral data discussed.     

Dimethyl Acetylenedicarboxylate in Reactions with Substituted 3‐(2‐aminophenyl)‐6‐R1‐1,2,4‐triazin‐5‐(2H)‐ones: Structure and Properties of the Products

The article describes unusual [5 + 1]‐cyclocondensations of dimethyl acetylenedicarboxylate (DMAD), in which this reagent uncharacteristically acts as a 1,1‐biselelectrophilic agent. Reactions of DMAD with 1,5‐bisnucleophilic 3‐(2‐aminophenyl)‐6‐R¹‐1,2,4‐triazin‐5(2H)‐ones yielded triazinoquinazoline‐derived diesters. The latter was shown to react with nucleophiles: hydrazine cleaved the pyrimidine ring of the diesters to give anilines, while ester hydrolysis furnished corresponding carboxylic acids.     

New Regioselective Synthesis and Biological Activity of Substituted 1H‐[1,2,4]Triazolo[3,4‐c][1,2,4]Triazoles

Two regioselective synthetic approaches for the title compounds 7 via reaction of hydrazonoyl halides 1 with 3‐methylthio‐5‐phenyl‐1,2,4‐triazole 3 and base‐catalyzed cyclization of N‐phenyl‐N‐(5‐phenyl‐s‐triazol‐3‐yl)thiohydrazides 6 are described. The mechanisms of the reactions studied and the biological activity of the isolated products 6 and 7 are pointed out.     

Synthesis of substituted 3‐(5‐amino‐[1,3,4]thiadiazol‐2‐yl)‐2H‐pyrano[2,3‐c]pyridin‐2‐ones

An efficient two‐step synthesis of novel 3‐(5‐amino‐[1,3,4]thiadiazol‐2‐yl)‐2H‐pyrano[2,3‐c]pyridine‐2‐ones was developed. In the first step, a new 2H‐pyrano[2,3‐c]pyridine‐3‐carboxamide 5 was prepared by Knoevenagel condensation of pyridoxal hydrochloride with cyanoacetamide. In the second step, the reaction of carboxamide 5 with a series of N⁴‐substituted thiosemicarbazides yielded a library of 35 dis crete compounds 8 {1–35} in high yields. The intermolecular recyclization mechanism leading to these products is discussed.     

A Convenient Synthesis of 2,3‐Dihydro‐4H‐thiopyrano[2,3‐b]‐, ‐[2,3‐c]‐, or ‐[3,2‐c]pyridin‐4‐ones by the Reaction of the Corresponding 1‐(Chloropyridinyl)alk‐2‐en‐1‐ones with NaSH

2,3‐Dihydro‐4H‐thiopyrano[2,3‐b]pyridin‐4‐ones 4 were prepared by a three‐step sequence from commercially available 2‐chloropyridine ( 1 ). Thus, successive treatment of 1 with ⁱPr₂NLi (LDA) and α,β‐unsaturated aldehydes gave 1‐(2‐chloropyridin‐3‐yl)alk‐2‐en‐1‐ols 2 , which were oxidized with MnO₂ to 1‐(2‐chloropyridin‐3‐yl)alk‐2‐en‐1‐ones 3 . The reactions of 3 with NaSH?n H₂O proceeded smoothly at 0° in DMF to provide the desired thiopyranopyridinones. Similarly, 2,3‐dihydro‐4H‐thiopyrano[2,3‐c]pyridin‐4‐ones 8 and 2,3‐dihydro‐4H‐thiopyrano[3,2‐c]pyridin‐4‐ones 12 were obtained starting from 3‐chloropyridine ( 5 ) and 4‐chloropyridine ( 9 ), respectively.     

Syntheses of N‐[3‐(1‐methyl‐1H‐2‐imidazolyl)propyl]benzamides and N‐[3‐(1‐methyl‐1H‐2‐imidazolyl)propyl]benzenesulfonamides

A series of substituted N‐(4‐substituted‐benzoyl)‐N‐[3‐(1‐methyl‐1H‐imidazol‐2‐yl)propyl]amines ( 13 ) and N‐arylsulfonyl‐N‐[3‐(1‐methyl‐1H‐imidazol‐2‐yl)propyl]amines ( 14 ) were prepared from the reaction of 3‐(1‐methyl‐1H‐imidazol‐2‐yl)propan‐1‐amine ( 7 ) with substituted benzoyl chloride or substituted‐benzene sulfonyl chloride respectively. Compound 7 was prepared by two independent methods.     

Simple and Efficient Synthesis of Novel 3‐Substituted 2‐Thioxo‐2,3‐dihydro‐1H‐benzo[g]quinazolin‐4‐ones and Their Reactions with Alkyl Halides and α‐Glycopyranosyl Bromides

A series of 3‐substituted 2‐thioxo‐2,3‐dihydro‐1H‐benzo[g]quinazolin‐4‐ones 4a – e were synthesized from the reaction of 3‐aminonaphthalene‐2‐carboxylic acid 1 with isothiocyanate derivatives 2a – e . The alkylation of 4a – e with alkyl halides gave 3‐substituted 2‐alkylsulfanyl‐2,3‐dihydro‐1H‐benzo[g]quinazolin‐4‐ones 5a – o . S‐Glycosylation was carried out via the reaction of 4a – e with glycopyranosyl bromides 7a and 7b under anhydrous alkaline conditions. The structure of the compounds was established as S‐nucleoside and not N‐nucleoside. Conformational analysis has been studied by homonuclear and heteronuclear two‐dimensional NMR methods (2D DFQ‐COSY, heteronuclear multiple quantum coherence, and heteronuclear multiple bond correlation). The S site of alkylation and glycosylation was determined from the ¹H and ¹³C heteronuclear multiple quantum coherence experiments.     

2‐(2‐Pyridyl­imino)‐2H‐1,2,4‐thia­diazo­lo­[2,3‐a]­pyridine

The title compound, C₁₁H₈N₄S, is found to have a symmetrical resonance structure in which both pyridyl‐N atoms interact with the S atom forming hemi‐bonds. This also results in the formation of a delocalized di­imine region and disturbance of the aromaticity in the pyridyl rings.     

Synthesis,Modification, and Anticonvulsant Activity of 3′‐R1‐Spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazolin]‐2,2′(7′H)‐diones Derivatives

Previously unknown 3′‐R¹‐5‐R²‐spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazoline]‐2,2′‐(7′H)‐diones and their N‐substituted analogues were obtained via reaction of 6‐R¹‐3‐(2‐aminophenyl)‐1,2,4‐triazin‐5‐ones with isatin and its substituted derivatives. It was shown that alkylation of 3′‐R¹‐5‐R²‐spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazolin]‐2,2′‐(7′H)‐diones by N‐R³‐chloroacetamides or chloroacetonitrile in the presence of а base proceeds by N‐1 atom of isatin fragment. The spectral properties (¹H and ¹³C NMR spectra) of synthesized compounds were studied, and features of spectral patterns were discussed. The high‐effective anticonvulsant and radical scavenging agents among 3′‐R¹‐5‐R²‐spiro[indoline‐3,6′‐[1,2,4]triazino[2,3‐c]quinazolin]‐2,2′(7′H)‐diones and their N‐substituted derivatives were detected. It was shown that compounds 2.2 , 2.8 , and 3.1 exceed or compete the activity of the most widely used in modern neurology drug—lamotrigine on the pentylenetetrazole‐induced seizures model. The aforementioned fact may be considered as a reason for further profound study of synthesized compounds using other pathology models.     

Azinoiminophosphorane mediated synthesis of 5H, 7H‐1,2,4‐triazolo[1,5‐c][1,3]benzoxazepin‐7‐ones and 6H,8H‐1,2,4‐triazolo‐[1,5‐c][1,3]oxazepin‐6‐ones

The aza‐Wittig reactions of benzophenone‐, acetophenone‐ and benzaldehyde l‐[(triphenylphosphoranyl‐idene)amino]ethylidenehydrazones (4) with phthalic anhydride, 2,3‐dimethylmaleic anhydride and 7‐oxabi‐cyclo[2,2,l]hept‐5‐ene‐2,3‐dicarboxylic anhydride ( 5a ) provide a new route to 5H,7H‐1,2,4‐triazolo[1,5‐c]‐[1,3]benzoxazepin‐7‐ones 8a‐c or 6H,8H‐1,2,4‐triazolo[1,5‐c][1,3]oxazepin‐6‐ones 8d‐h via the thermal reaction of the expected azinoimine lactones 6 .     

Synthesis of some novel 3,7‐dimethyl‐4H‐pyrazolo[5,1‐c][1,2,4]triazin‐4‐ones

Some novel 3,7‐dimethyl‐6H‐pyrazolo[5,1‐c][1,2,4]triazin‐4‐ones were prepared (3a‐g) . Compounds 3a,b were treated with hydrazines to afford various products 7a,b, 8a,b, 9 and lla,b depending on the type of hydrazine derivative and reaction conditions. The benzoyloxyimino‐pyrazolo[5,1‐c][1,2,4]triazines (13a,b) were synthesized by refluxing of compounds 3a,b with hydroxylamine hydrochloride to afford the corresponding oxime derivatives followed by treatment with benzoyl chloride.     

Efficient One‐Pot Syntheses of 7‐Alkyl‐6H,7H‐naphtho[1,2:5,6]pyrano‐[3,2‐c]chromen‐6‐ones by 1‐Methyl‐3‐(2‐(sulfooxy)ethyl)‐1H‐imidazol‐3‐ium Chloride

An efficient synthesis of 7‐alkyl‐6H,7H‐naphtho‐[10,20:5,6]pyrano[3,2‐c]chromen‐6‐ones by three‐component condensation reaction of β‐naphthol, aromatic aldehydes, and 4‐hydroxycoumarin catalyzed by 1‐methyl‐3‐(2‐(sulfooxy)ethyl)‐1H‐imidazol‐3‐ium chloride is reported in good to excellent yields and short reaction times.     

2‐[6‐(1H‐Benzimidazol‐2‐yl)‐2‐pyridyl]‐1H‐benzimidazol‐3‐ium perchlorate monohydrate

The title compound, C₁₉H₁₄N₅⁺·ClO₄^?·H₂O, contains planar C₁₉H₁₄N₅⁺ cations, perchlorate anions and water mol­ecules. The two closest parallel cations (plane‐to‐plane distance of 3.41 Å), together with two neighbouring perchlorate anions and two water mol­ecules, form an electrically neutral quasi‐dimeric unit. Two acidic H atoms of the cation, both H atoms of the water mol­ecule, the N atoms of the imidazole rings and three of the four O atoms of the perchlorate anion are involved in the hydrogen‐bonding network within the dimeric unit. The remaining third acidic H atom of the imidazole rings and the water mol­ecules complete a two‐dimensional network of hydrogen bonds, thus forming puckered layers of dimers. The angle between the planes of two neighbouring dimeric units in the same layer is 33.25 (3)°.     

Synthesis and reactions of 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]‐quinazolin‐9‐one and 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one

The reaction of 3‐N‐(2‐mercapto‐4‐oxo‐4H‐quinazolin‐3‐yl)acetamide ( 1 ) with hydrazine hydrate yielded 3‐amino‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 2 ). The reaction of 2 with o‐chlorobenzaldehyde and 2‐hydroxy‐naphthaldehyde gave the corresponding 3‐arylidene amino derivatives 3 and 4 , respectively. Condensation of 2 with 1‐nitroso‐2‐naphthol afforded the corresponding 3‐(2‐hydroxy‐naphthalen‐1‐yl‐diazenyl)‐2‐methyl‐3H‐[1,2,4]triazolo[5,1‐b]quinazolin‐9‐one ( 5 ), which on subsequent reduction by SnCl₂ and HCl gave the hydrazino derivative 6. Reaction of 2 with phenyl isothiocyanate in refluxing ethanol yielded thiourea derivative 7. Ring closure of 7 subsequently cyclized on refluxing with phencyl bromide, oxalyl dichloride and chloroacetic acid afforded the corresponding thiazolidine derivatives 8, 9 and 10 , respectively. Reaction of 2‐mercapto‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 11 ) with hydrazine hydrate afforded 2‐hydrazino‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 12 ). The reactivity 12 towards carbon disulphide, acetyl acetone and ethyl acetoacetate gave 13, 14 and 15 , respectively. Condensation of 12 with isatin afforded 2‐[N‐(2‐oxo‐1,2‐dihydroindol‐3‐ylidene)hydrazino]‐3‐phenylamino‐3H‐quinazolin‐4‐one ( 16 ). 2‐(4‐Oxo‐3‐phenylamino‐3,4‐dihydroquinazolin‐2‐ylamino)isoindole‐1,3‐dione ( 17 ) was synthesized by the reaction of 12 with phthalic anhydride. All isolated products were confirmed by their ir, ¹H nmr, ¹³C nmr and mass spectra.     

Synthesis of novel 2‐alkoxy(aralkoxy)‐4H‐[1,2,4]triazolo[1,5‐a]quinazolin‐5‐ones starting with dialkyl‐N‐cyanoimidocarbonates

A novel series of 2‐alkoxy(aralkoxy)‐4H‐[1,2,4]triazolo[1,5‐a]quinazolines were synthesized employing N‐cyanoimidocarbonates and 2‐hydrazinobenzoic acid as building blocks. Chemical transformation of the inherent lactam moiety in the targeted 2‐alkoxy(aralkoxy)[1,2,4]triazolo[1,5‐a]quinazolines was offered access to a variety of derivatives. J. Heterocyclic Chem., (2011).     

10‐Ethyl‐3‐(4‐methoxy­phenyl)‐1,2,4‐triazolo­[4′,3′:2,3]‐1,2,4‐triazino[5,6‐b]­indole

Oxidative cyclization of 5‐ethyl‐3‐(4‐methoxy­benzyl­idene)­hydrazino‐1,2,4‐triazino­[5,6‐b]­indole gave the linearly annel­ated title compound, C₁₉H₁₆N₆O. The skeleton is approx­imately planar, except for the ethyl group.     

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.