Synthesis and antimicrobial activity of new benzofuranyl‐1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones

New benzofuranyl‐1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones are synthesized in which benzofuran is coupled with 1,3‐benzoxazines and 1,3‐benzoxazin‐2‐ones through ‐CONH‐ and ‐COCH₂‐ bridges, respectively. The antimicrobial activity of these compounds is reported.     

Synthesis of new chromeno[4,3,2‐de]quinazolin‐2‐ones, ‐quinazolines and ‐pyrrolo[2,1‐b]quinazolines

The total synthesis of chromeno[4,3,2‐de]quinazolin‐2‐ones, ‐quinazolines and ‐pyrrolo[2,1‐b]quinazolines from easily prepared 4‐methoxy‐1‐nitro‐9H‐xanthen‐9‐one is reported. These compounds, in which a 1,3‐diazine ring is fused to the xanthene scaffold, were obtained with good overall yields in very few steps.     

Synthesis and reactions of 2‐chloro‐2‐(hydroximino)‐1‐(4‐methyl‐2‐phenylthiazol‐5‐yl)ethanone

3‐Nitrosoimidazo[1,2‐a]pyridine, 3‐nitrosoimidazo[1,2‐a]pyrimidine, 3‐nitrosoquinoxaline, 2‐nitroso‐4H‐benzo[b]thiazine, 2‐nitroso‐4H‐benzo[b]oxazine, isoxazoles, isoxazolo[3,4‐d]pyridazines and pyrrolo[3,4‐d]isoxazole‐4,6‐dione were synthesized from 2‐chloro‐2‐(hydroximino)‐1‐(4‐methyl‐2‐phenylthiazol‐5‐yl)ethanone and different reagents. Structures of the newly synthesized compounds were confirmed by elemental analysis and spectral data.     

Reactions of cephalosporin sulfones 3. Synthesis of 2‐phenylhydrazonocephem‐sulfones. A new potential entry to 2‐aminocephems

Reaction of cephem sulfones 1a‐e with aryldiazonium salts gives the 2‐azo compounds which immediately rearrange into the corresponding 2‐hydrazono derivatives 2a‐e .     

Reactions of α‐diazoketones with indolinone imines: Synthesis of new 1,3,3‐triaryl‐1′‐methylspiro[azetidine‐2,3′‐indoline]‐2′,4‐diones

The paper describes the synthesis of new 1,3,3‐triary‐1′‐methylspiro[azetidine‐2,3′‐indoline]‐2′,4‐diones from reaction of the 2‐diazo‐1,2‐diarylethanones with 3‐arylimino‐1‐methyl‐2‐indolinones. The compounds have been characterized by satisfactory analytical and spectral (IR, ¹H NMR and ¹³C NMR) data. The diarylketenes, generated in situ from thermal decomposition of the 2‐diazo‐1,2‐diarylethanones, react with azomethine linkage in preference to carbonyl group leading to the formation of products.     

Synthesis and herbicidal activity of 2‐(3‐(trifluoromethyl)‐5‐(alkoxy)‐1H‐pyrazol‐1‐yl)‐4‐aryloxypyrimidine derivatives

A series of 2‐(3‐(trifluoromethyl)‐5‐(alkoxy)‐1H‐pyrazol‐1‐yl)‐4‐aryloxypyrimidine derivatives were designed and synthesized. The structures of all the title compounds were confirmed by ¹H NMR and elementary analysis. These compounds were screened for herbicidal activity against rape and barnyard grass. Compound B13 exhibited moderate herbicidal activity.     

Reaction of 2‐diazo‐1,2‐diarylethanones with benzophenone n‐(diaryl)acyl hydrazones: Formation of 1,3,4‐oxadiazolines

The reaction of 2‐diazo‐1,2‐diarylethanones with benzophenone N‐(diaryl)acyl hydrazones leads to the formation of 1,3,4‐oxadiazolines. The products have been characterized on the basis of satisfactory analytical and spectral (IR, ¹H and ¹³C NMR, and Mass) data. The mechanism for the formation of products through the reaction of diarylketenes, generated in situ from thermal decomposition of the 2‐diazo‐1,2‐diarylethanones, with imino nitrogen and intramolecular [2 + 3] dipolar cycloaddition is suggested.     

Design,synthesis and biological evaluation of novel 6,7,8,9‐tetrahydro‐2‐(2‐aryloxypyrimidin‐4‐yl)‐2H‐[1,2,4]triazolo[4,3‐a]azepin‐3(5H)‐ones

A series of novel 6,7,8,9‐tetrahydro‐2‐(2‐aryloxypyrimidin‐4‐yl)‐2H‐[1,2,4]triazolo[4,3‐a]azepin‐3(5H)‐ones were designed and efficiently synthesized. Their structures were determined by IR, ¹³C and ¹H NMR, mass spectroscopy, and elemental analysis. These compounds were screened for herbicidal activities against rape and barnyard grass. Compounds 5a‐5f and 5m exhibited moderate herbicidal activity against rape. In addition, the synthesis of the intermediate 1‐(azepan‐2‐ylidene)‐2‐(2‐chloropyrimidin‐4‐yl)‐hydrazine ( 3 ) was studied and the reason for the low yield in the initial procedure is discussed as well.     

Rapid and efficient microwave assisted method for the regioselective synthesis of 8,8′‐methylene‐bis‐4‐oxo‐1H and 2H‐chromeno[4,3‐C]pyrazoles

The ethyl ester of 5,5′‐methylene‐bis‐salicyclic acid 3 was prepared by the esterification of 5,5′‐methylene‐bis‐salicylic acid 2 . The compound 3 on reacting with ethylacetoacetate yields 6,6′‐methylenebis‐(3‐acetyl‐4‐hydroxycoumarin) 4 . The compound 4 was regioselectively converted into either 8,8′‐methylene‐bis‐(4‐oxo‐1H‐chromeno[4,3‐c]pyrazoles) 6 or 8,8′‐methylene‐bis(‐4‐oxo‐2H‐chromeno[4,3‐c]‐pyrazoles) 7 under microwave irradiation. High yields are achieved even on a gram scale, while reaction times are considerably shortened compared to conventional heating conditions.     

The [3 + 2] cycloaddition route to 5‐carbomethoxy‐4h‐1,2,3‐triazolo[1,5‐a][1]benzazepines from baylis‐hillman acetates of 2‐azidobenzaldehydes

A new, simple synthesis of 5‐carbomethoxy‐4H‐1,2,3‐triazolo[1,5‐a][1]benzazepines from the reaction of several Baylis‐Hillman acetates of 2‐azidobenzaldehydes with alkynide Grignard reagents such as phenylethynyl‐, 1‐propynyl‐ and ethynylmagnesium bromides followed by cycloaddition reaction has been described.     

A general and versatile synthesis of 3‐phenylthio β‐lactams as lead molecules for 3‐methyl‐2‐azetidinones

Ketene‐imine cycloaddition using phosphorus oxychloride and benzenesulfonyl chloride under the described reaction conditions yielded trans 3‐phenylthio 2‐azetidinones in good yields. Desulfurization using Raney nickel and alkylation finally afforded trans 3‐methyl‐2‐azetidinones in a stereoselective manner.     

Synthesis and spectral data of new 1,2‐bis‐(2‐hetaryl‐4‐oxothiazolidin‐3‐yl)ethanes and 1,4‐bis‐(2‐hetaryl‐4‐oxothiazolidin‐3‐yl)butanes

New αω‐bis‐(2‐hetaryl‐4‐oxothiazolidin‐3‐yl)alkanes were prepared via a common two step procedure using N,N‐bis‐hetarylidenamines condensation with α‐mercaptoacetic acid. The used bis‐aldimines were obtained from reaction between ethylenediamine or putrescine and benzaldehyde or the isomeric pyridinecarboxyaldehydes. The bis‐(2‐phenyl‐4‐oxothiazolidin‐3‐yl)alkanes were prepared by one‐pot three component reaction of diamine, aldehyde and α‐mercaptoacetic acid under very mild conditions.     

Retro‐ene reactions in heterocyclic synthesis. v. a novel synthetic method for 1,3,5‐triazine‐2,4(1H,3H)‐diones

N‐t‐Butylamidines 1 on heating with diphenyl carbonate ( 2 ) at 150‐180° gave the 1,3,5‐triazine‐2,4(1H,3H)‐dione derivatives 5 . Acylation of amidines 1 and cyclocondensation of the resulting carbamates 3 gave [1,3,5,7]tetrazocine‐2,6‐dione derivatives 4 , and subsequent retro‐ene reaction and ring contraction afforded triazine derivatives 5 .     

Synthesis of 1‐(substituted phenylcarbonyl/sulfonylamino)‐1,2,3,6‐tetrahydropyridine‐5‐carboxylic acid diethylamides as potential anti‐inflammatory agents

Fifteen novel 1‐(substituted phenylcarbonyl/sulfonylamino)‐1,2,3,6‐tetrahydro‐ pyridine‐5‐carboxylic acid diethylamide ( 7, 15 ) were synthesized in fair to good yields via sodium borohydride reduction of the corresponding 1‐(substituted phenylcarbonyl/ sulfonylimino)‐3‐diethylcarbamoyl pyridinium ylides ( 6, 14 ) in absolute ethanol.     

Synthesis of benzo[c][1,8]phenanthrolin‐6‐one through cyclization of N‐(isoquinol‐5‐yl)‐2‐bromo‐benzamide derivatives

In the course of our search for compounds with potential antitumor properties we have undertaken the synthesis of benzo[c][1,8]phenanthroline derivatives. Our project required the preparation of 8,9‐dimethoxy benzo[c][1,8]phenanthrolin‐6‐ones. This was first attempted by the lithiumdiisopropylamide cyclization of N‐(isoquinol‐5‐yl)‐2‐bromo‐4,5‐dimethoxybenzamide. The reaction led to 40% of the unexpected internal Diels‐Alder adduct 3,4‐dimethoxy‐6H‐pyrido[2,3‐i]6,8a‐ethenoindolo[cd]isoquinoline‐2(1H)‐one, which arose from a benzyne intermediate. In a second and more successful approach, the internal biaryl palladium diacetate‐assisted coupling reaction of properly N‐protected N‐(isoquinol‐5‐yl)‐2‐bromo‐4,5‐dimethoxybenzamide was studied. The optimisation of the protecting group necessary for this procedure led to a 64% yield of the target compound starting from N,N‐(isoquinol‐5‐yl)‐bis‐(2‐bromo‐4,5‐dimethoxybenzamide).     

Synthesis and tautomerization of 6,7‐dihydro‐(1,2,3)‐triazolo[1,5‐a]pyrimidines

The condensation of 5‐amino‐4‐phenyl‐1,2,3‐triazole ( 1 ) with chalcones 2a‐e or 3‐dimethylamino‐propiophenone ( 4f ) leads to the 6,7‐dihydro‐(1,2,3)‐triazolo[1,5‐a]pyrimidines 3a‐f. The equilibrium of 3 and the tautomeric 4,7‐dihydro‐(1,2,3)‐triazolo[1,5‐a]pyrimidines 3′ is described.     

Cyclocondensation reactions of heterocyclic carbonyl compounds XII. The double course of cyclization of 3‐(2‐aminobenzyl)‐1,2‐dihydro‐quinoxaline‐2‐one

The cyclocondensation reaction of compound 1 in boiling hydrochloric acid had an unexpected course. Instead of supposed 5,11‐dihydro‐quinoxalino[2,3‐b]quinoline 6a , 2‐(indol‐2‐yl)‐benzimidazole 4 was isolated as the major product.     

Synthesis of 9‐[1‐benzyl‐5‐(alkylsulfonyl)‐1H‐2‐imidazolyl]perhydro‐1,8‐acridinediones

Tricyclic dihydropyridines like ZM244085 are potential K_ATP channel openers. In this study 3‐cyanophenyl ring of ZM244085 was replaced with imidazolyl ring. So, 9‐[1‐benzyl‐5‐(alkylsulfonyl)‐1H‐2‐imidazolyl]perhydro‐1,8‐acridinediones ( 5d‐f ) were synthesized from 2‐alkylsulfonyl‐1‐benzyl‐5‐formylimidazole ( 4d‐f ) and cyclohexane‐1,3‐dione according to classical Hantzch synthesis as potential potassium channel modulators.     

An efficient one‐pot synthesis of n‐carboxymethylacridine‐1,8‐dione derivatives under microwave irradiation

A series of N‐carboxymethylacridine‐1,8‐dione derivatives were synthesized by one‐pot reaction of aldehyde, dimedone and glycine in glycol under microwave irradiation without catalyst with excellent yields (78‐92%) and short reaction time (4‐8min). And the reaction was not only suitable for aromatic monoaldehyde, but also aromatic dialdehyde.