Oxalic acid as a versatile catalyst for one pot facile synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐ones and their thione analogues

3,4‐Dihydropyrimidin‐2‐(1H)‐ones and their thione analogues are synthesized from the condensation of aromatic aldehydes, β‐dicarbonyl compound and urea or thiourea in presence of 5 mol% of oxalic acid in ethanol‐water (1:2; v/v) under mild reaction conditions. The yields obtained are better and also the use of very inexpensive catalyst, environmentally benign solvent and easy work‐up are the advantageous aspects of the present method.     

Protonation of 2H‐Azaphosphirene Complexes: P?N Bond Activation and Ring‐Expansion Reactions

P? N bond activation of 2H‐azaphosphirene complexes 1 and 2 by using triflic acid led to ring expansion in the presence of nitriles. In the absence of nitriles, the reaction surprisingly afforded two haptomeric N‐protonated 1‐aza‐3‐phospha‐butadiene complexes in the case of complex 1 , whereas the N‐protonated 2H‐azaphosphirene complex [H‐ 2 ]⁺ was characterized by NMR spectroscopy.

     

A three‐component,one‐pot synthesis of oxazinoquinolin‐3‐one derivatives

Oxazino[5,6‐f]quinolin‐3‐one derivatives have been synthesized in a one‐pot, and efficient process by condensation of 6‐quinolinol, aromatic aldehydes and urea under microwave‐assisted and thermal solvent‐free conditions.     

Synthesis of a new class of sulfone linked bisheterocycles

Some bisheterocycles having pyrrole and oxazoline/thiazoline units were synthesized from Z‐styrylsulfonylacetic acid methyl esters using samarium chloride.     

Phenacylsulfonylacetic acid methyl ester‐synthon for 1,2,3‐selena/thiadiazoles and 2H‐diazaphospholes

A new class of 1,2,3‐selena/thiadiazoles and 2H‐diazaphospholes were synthesized by exploiting α‐ketomethylene group in phenacylsulfonylacetic acid methyl ester.     

Application of the acetate of baylis‐hillman adducts of salicylaldehydes in the synthesis of methyl 2‐oxo‐2,3‐dihydrobenzo[b]oxepine‐4‐carboxylates

A simple synthesis of several methyl 2‐oxo‐2,3‐dihydrobenzo[b]oxepine‐4‐carboxylates from Baylis‐Hillman adducts of O‐benzyl protected 2‐hydroxybenzadehydes has been described through the acetylation, cyanation, debenzylation, as well as acid assisted Pinner cyclization.     

A novel synthesis of benzo[h]quinolines and study of their fluorescence properties

An elegant synthesis of highly fluorescent benzo[h]quinolines have been accomplished from readily available and highly economical 6‐methoxy‐1‐tetralone in high purity and excellent yield.     

Metathetic approach towards macrocyclic bis‐ethers and in sequence use of barbier reaction and RCM for spirocyclic ethers

An efficient method for the synthesis of novel macrocyclic bis‐ethers from alizarin and also some new spiro ethers from various substituted ketones by the use of Barbier and ring‐closing metathesis (RCM) reactions has been developed.     

Phosphomolybdic acid catalyzed facile one‐pot synthesis of 2,4,5‐triaryl‐1H‐imidazoles from benzil and aromatic aldehydes

A facile one‐pot synthesis of 2,4,5‐triaryl‐1H‐imidazoles with better yields and shorter reaction time from the condensation of benzil, ammonium acetate and aromatic aldehydes using the catalyst phosphomolybdic acid is described     

New one‐ pot synthesis of pyrazolo[3,4‐c]pyridazine and isoxazolo‐[5,4‐b]pyridine derivatives from potassium cyanoacetahydroxamate

The reaction of potassium cyanoacetohydroxamate 1 with ethyl 2‐aryl‐hydrazono‐3‐oxobutyrates 2 gave the unexpected pyrazolo[3,4‐c]pyridazines 7 and isoxazolo[5,4‐b]pyridines 10 via a one‐pot reaction. A mechanistic proof is suggested to account for the products.     

Synthesis of novel 3,5,7‐triaryl‐5,6‐dihydro‐4h‐1,2,5‐triazepines

Several hitherto unknown 3,5,7‐triaryl‐5,6‐dihydro‐4H‐1,2,5‐triazepines have been synthesised by cyclocondensation of N,N‐bis(phenacyl)anilines with hydrazine hydrate in ethanol or ethyleneglycol under reflux condition. Increased yields were obtained in the presence of p‐toluenesulfonic acid compared to the uncatalysed reaction.     

An improved synthesis of 1‐acetyl‐1H‐indol‐3‐yl acetates

An efficient two steps procedure for the synthesis of 1‐acetyl‐1H‐indol‐3‐yl acetates, starting from 2‐chlorobenzoic acids, was developed and in general, moderate to good yields were obtained     

An interesting cyclization of N‐methyl‐3‐phenyl‐N‐(2‐(Z)‐phenylethenyl)‐cis‐oxiranecarboxamide

Under Lewis acid condition, N‐methyl‐3‐phenyl‐N‐(2‐(Z)‐phenylethenyl)‐cis‐oxiranecarboxamide undergoes elegant double cyclizations to give interesting products.     

One‐pot synthesis of symmetrically disubstituted 3H‐phenoxazin‐3‐ones by selective oxidative condensation with LTA

A one‐pot synthesis of some new 2,8‐disubstituted 3H‐phenoxazin‐3‐ones from 4‐substituted‐2‐aminophenols through a selective oxidative condensation by lead tetraacetate in acetic acid is described.     

Synthesis and antimicrobial activity of novel spirocompounds with pyrazolone and pyrazolthione moiety

The paper focuses on the utility of 2‐pyrazoline‐5‐ones and 2‐pyrazoline‐5‐thiones as active Michael donors for the synthesis of novel spirocyclohexanone derivatives. The sulphur containing compounds when screened for antimicrobial activity showed promising inhibition of S. Typhi, S Aures and E Coli bacteria.     

1,3‐Dipolar cycloadditions: Investigation of cycloadditions of c‐aryl‐n‐(4‐chlorophenyl) nitrones to n‐cinnamoyl piperidines

Investigation of cycloadditions of C‐aryl‐N‐(4‐chlorophenyl)nitrones to N‐cinnamoyl piperidines was carried out. Two diastereoisomeric and one regioisomeric cycloadducts, and in some cases ring‐opened compounds were characterized by spectroscopic and X‐ray data. Molecular modelling was carried out for conformational studies.     

Unexpected formation of pyridodiindole derivatives with cytotoxic activity via double nenitzescu reaction

The title compounds 10 and 11 were prepared by a one‐step procedure from 1,4‐benzoquinone ( 4 ) and pyridine‐2,4,6‐triamine ( 5 ) via an extension of the Nenitzescu reaction     

A convenient synthesis of novel 1,3,4‐triaryl‐3,4‐dihydropyrimidin‐2(1H)‐ones by cyclization of aromatic isocyanates with β‐arylamino‐1‐phenylpropan‐1‐ones

A simple one‐step method for preparation of novel 1,3,4‐triaryl‐3,4‐dihydropyrimidin‐2(1H)‐ones has been developed by reaction of aromatic isocyanates with β‐arylamino‐1‐phenylpropan‐1‐ones in refluxing toluene in the presence of KHSO₄ and HCl.     

A new method for the synthesis of bicyclic pyran acetals

cis‐Fused bicyclic acetals were obtained from the unusual cyclization reaction between diols and dihydropyran. Furothiopyran, substituted pyranopyrans, and pyranooxepine and pyranobenzoxepine compounds were obtained with high diastereoselectivity and cis‐diastereomers were obtained in high yields.     

Synthesis of two potential heterocyclic amine food mutagens

The syntheses of two potential food mutagens formed during cooking, 2‐amino‐3,6,7‐trimethyl‐3H‐imidazo[4,5‐b]pyridine ( 1 ) and 2‐amino‐3,6,7‐trimethyl‐3H‐imidazo[4,5‐c]pyridine ( 2 ), are described.