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An environmentally benign approach in aqueous medium by means of Lewis acid catalyst affords a wide spectrum of pyrazoline derivatives in satisfactory yields. [3+2] cycloaddition reactions of substituted azomethine‐N‐imines to maleimide in aqueous medium at relatively high concentrations of Lewis acid catalyst have emerged as an environment friendly alternative to conventional solvents. Promising catalytic activity has been revealed by Lewis acid like Cu (NO3)2 in aqueous medium. The obvious features of this synthetic protocol were short reaction time, high efficiency, less hazardous synthesis by benign solvent, catalysis, modest workup, and a clean reaction methodology. [ABSTRACT FROM AUTHOR]

2-Thioxo-1,3-oxazepine-4,7-dione compounds were obtained via triethylamine-catalyzed condensation of maleamic acids with thiophosgene under anhydrous conditions. This method features relatively a simple methodology, use of inexpensive reagents, convenient operating conditions and high yields. [ABSTRACT FROM AUTHOR]

An atom economic and facile synthesis of novel dispiro-oxindole-pyrrolidines has been achieved via a three-component tandem of azomethine ylide generated in situ from isatin and sarcosine by decarboxylative condensation with N-aryl-3-benzylidene-pyrrolidine-2,5-dione derivatives as dipolarophiles. The salient features of synthetic procedure are characterized by the mild reaction conditions, high yields, high regioselectivity and stereoselectivity, , and operational simplicity. This regioselectivity was assumed to be under the influence of π-π stacking interactions between the aromatic rings of azomethine ylide and N-aryl-3-benzylidene-pyrrolidine-2,5-diones that further control the exo-endo selectivity of the reaction . The regiochemistry and structures of the cycloadducts were determined with spectroscopic data. [ABSTRACT FROM AUTHOR]

of C, N-diphenylnitrones 1 to N-aryl maleimides 2 afforded two diastereomeric isoxazolidines with high selectivity. The structure and steric configuration of the adducts have been assigned on the basis of 1H NMR, 1H NMR COSY, 13C NMR and IR spectroscopy. The π-π stacking interactions between maleimide's and nitrone's aromatic rings during the were assumed to control the exo-endo selectivity of the reaction. Thus, the exo-endo ratio depends upon the position of the substituent present on the C-phenyl ring of the C, N-diphenylnitrones. [ABSTRACT FROM AUTHOR]

Through the normal mode of of N-(α-cyano-α-aryl)-methylanilines ( II) onto N-sulphinylanilines ( III) has provided 2,3,5-triaryl-4-imino-2H,3H,5H-[1,2,5]thiadiazolidin-1-oxides ( IV). The present protocol has advantage of convenient operation to synthesize heterocyclics in good yield. [ABSTRACT FROM AUTHOR]

1,3-Dipolar cycloaddition of nitrilimines 3 with N-benzyl maleimide 4 has provided 5-benzyl-1-(2′,4′-dibromophenyl)-3-(4″-substituted phenyl)-3a,4,6,6a-tetrahydro-1 H,5 H-pyrrolo[3,4- c]pyrazole-4,6-dione derivatives 5 in excellent yield as the only isomer through a concerted pathway. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

In this protocol, synthesis of novel 2,5-diphenyl-3,3-spiropentamethylene-5H-2,3,3a,6a-tetrahydropyrrolo[3,4-d]isoxazole-4,6-diones through [3 + 2] cycloaddition of N-cyclohexylidene N-phenyl nitrones with cyclic dipolarophiles is described. 1,3-Dipolar cycloaddition of nitrones with substituted N-arylmaleimides gives exclusivelyendo-diastereoisomers of spiro-isoxazolidines and their stereochemistry was assigned using1H NMR and1H-1H correlation spectroscopic studies. [ABSTRACT FROM AUTHOR]

Abstract: The synthesis of some biologically interesting pyrrolo-isoxazolidine derivatives was accomplished by the 1,3-dipolar cycloaddition reaction of substituted azomethine N-oxides 1 with substituted N-aryl maleimides 2 leading to the formation of new stereoisomeric 2,3,5-triaryl-4H,2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione derivatives 3 in excellent yields. The synthesized compounds have been screened for their advanced glycation end (AGE) product formation inhibitory activity on the basis of their ability to inhibit the formation of AGEs in the bovine serum albumin (BSA)-glucose assay. All the synthesized compounds have been found to exhibit significant activity against AGE formation. [Copyright &y& Elsevier]

The azomethine N-oxides ( 1) on reacting with N-benzylmaleimide ( 2) provide a mixture of stereoisomers 2,3-diphenyl-5-benzyl-4 H-2,3,3a,5,6,6a-hexahydropyrrolo[3,4- d]isoxazole-4,6-dione derivatives ( 3) in good yields. These isomers have been assigned cis and trans configurations ( 3-A and 3-B) with respect to proton C3-H on the azomethinic carbon on the basis of their PMR and H-NMR COSY data. The ratio between cis and trans isomers has been found to be dependent on substituents present at ortho position of C-phenyl aldehydic moiety. The salient feature of these 1,3-dipolar cycloaddition reactions lies in that the benzylic protons on N-benzyl moiety suffer gem coupling, indicating magnetic nonequivalence. J. Heterocyclic Chem.,, (2012). [ABSTRACT FROM AUTHOR]

1,3-Dipolar cycloaddition of nitrilimines, generated in situ from hydrazonoyl bromides (I), with N-benzylmaleimide provides stereoselectively the cis-fused pyrrolopyrazole derivatives (III) (9 examples) in good yield. [ABSTRACT FROM AUTHOR]

The solvent- and catalyst-free synthesis of spiro-isoxazolidines (III) and (V) with one endo-diastereoisomer is achieved by using the stable N-oxides (I) and (IV) and electron-rich and electron-deficient N-phenylmaleimides (II). [ABSTRACT FROM AUTHOR]

Abstract: A series of 2,3-diphenyl-5-(naphthalen-1-yl)-4H-2,3,3a,5,6,6a-hexahydropyrrolo[3,4-d]isoxazole-4,6-dione derivatives were synthesized via 1,3-dipolar cycloaddition of azomethine N-oxides with N-(α-naphthyl)maleimide. The pyrrolo-isoxazole derivatives were assigned cis- and trans- configurations (3-A and 3-B) with respect to proton C3-H on azomethinic carbon on the basis of their 1H NMR. The reaction proceeds through cis- endo addition rule indicating the predominance of cis isomer. The cis- and trans- isomers of a prototype compound 3a i.e., compound 3a-A and compound 3a-B were evaluated for anti-stress activity in immobilization-induced acute stress. Compound 3a-A (5 and 10 mg/kg) and compound 3a-B (10 mg/kg) attenuated immobilization stress-induced behavioral alterations in Swiss albino mice suggesting that pyrrolo-isoxazole may serve as lead molecule for the development of anti-stress agents. [Copyright &y& Elsevier]

The article presents chemical equations related to an article on regioselective synthesis of spirocyclic compounds through the cycloaddition reaction of azomethine ylide by A. Kaur and others, published in the periodical "Journal of Organic Chemistry" in 2015.

A new and efficient method for ortho-amidoalkylation of phenols via Mannich-type condensation with formaldehyde and lactams using recyclable solid acid catalyst is described. This is the first report for ortho-amidoalkylation of phenols by lactams via Mannich-type condensation. LC-ESI-MS/MS based mechanistic study revealed that reaction proceeds through o-quinone methide (o-QM) and an oxazine intermediate via tandem Knoevenagel condensation, formal [4 + 2]-Diels--Alder cycloaddition and acid catalyzed oxazine ring-opening. [ABSTRACT FROM AUTHOR]