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In a one-pot synthesis, 1′-methyl-2,3″-dioxo-5″-aryl-1,2,5a″,7″,8″,9a″-hexahydro-5″H,6″H-dispiro[indole-3,2′-pyrrolidine-3′,2″-pyrano[2,3-d][1,3]thiazolo[3,2-a]pyrimidine]-4′-carboxylic acid methyl ester was prepared via the sequential reaction of 4-aryl-octahydro-pyrano[2,3-d]pyrimidine-2-thione, dimethyl acetylenedicarboxylate (DMAD), and a mixture of isatin and sarcosine. All the novel spiro compounds, in moderate yields, were characterized thoroughly by infrared, NMR, mass spectromentry, and elemental analysis together with x-ray crystallographic analysis.

A novel series of (9Z)-9-arylmethylidene-3-(2,6-dichlorophenyl)-5,6-dihydro[1,3]thiazolo[2′,3′:2,3]imidazo [1,2-d][1,2,4]oxadiazol-8(9H)-one derivatives were prepared in moderate yields by the 1,3-dipolar cycloaddition reaction of a nitrile oxide with (2Z)-2-arylmethylidene-5,6-dihydroimidazo [2,1-b][1,3]thiazol-3(2H)-ones. The reaction site of the dipolarphile is the C═N of imidazo[2,1-b][1,3]thiazole rather than the expected C═C of the arylmethylidene. The product structures were characterized thoroughly by IR, MS, NMR spectroscopy, and elemental analysis. The results indicate that this reaction proceeds with chemoselectivity and regioselectivity.

The 1,3-dipolar cycloaddition of azomethine ylide generated in situ from isatin and sarcosine to 2-arylmethylidene-2,3-dihydro-1H-pyrrolizin-1-ones afforded novel 1′-methyl-4′-(aryl)-1″H-dispiro[indole-3,2′-pyrrolidine-3′,2″-pyrrolizine]-1″,2(1H)-diones in good yields. The structures of all the products were characterized thoroughly by NMR, infrared spectroscopy, mass spectrum, and elemental analysis.

The 1,3-dipolar cycloaddition of an azomethine ylide generated by a decarboxylative route from sarcosine and isatin to 7-arylmethylidene-3-aryl-3,4-dihydro-2H-thiazolo[3,2-a][1,3,5]triazin-6(7H)-ones afforded novel dispiro[oxindole-pyrrolidine]-thiazolo[3,2-a][1,3,5]triazines in moderate yields. The structures of the products were determined and characterized thoroughly by NMR, MS, IR, and elemental analysis. The results of experiment indicated that this 1,3-dipolar cycloaddition proceeded with high stereoselectivity and regioselectivity. J. Heterocyclic Chem., (2011).

The 1,3-dipolar cycloaddition reaction of thiazolo[3,2-a]pyrimidine derivatives (I) with in situ from N-phenyl benzhydrazidoyl chloride (II) generated nitrilamine is investigated.

Active methylene compounds such as 5,5-dimethylcyclohexane-1,3-dione, cyclohexane-1,3-dione, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one, 1,3-dimethyl-1H-pyrazol-5(4H)-one, and 3-methylisoxazol-5(4H)-one react with the 3-C position of N-confused porphyrin in THF for 5 min to afford a novel type of N-confused porphyrin derivatives in good yield without the need of any catalyst.

The 1,3-dipolar cycloaddition of thiazolo[3,2-a]triazine derivative (I) to azomethine ylide, generated in situ from sarcosine and acenaphthenequinone, affords novel spiro compounds (IV).

A range of novel aryl-substituted trispiroheterocycles (VI) is prepared with high regio- and stereoselectivity via a tandem cycloaddition reaction of 2,5-bis(arylmethylidene)cyclopentanones (III).

Azomethine ylides, derived from isatin and sarcosine or proline, react with substrates of type (I)/(V) to give the novel dispiroheterocycles regio- and stereoselectively.

A new class of [1,2,4]oxadiazolo[4,5-a]thiazolo[2,3-b]pyrimidin-9(10H)-one was prepared in moderate yields by the reaction of nitrile oxide with 2-arylmethylidene-6,7-dihydro-5H-thiazolo[3,2-a]pyrimidin-3-one. The reaction site of dipolarphile is the CN of thiazolo[3,2-a]pyrimidin-3-one rather than the expected CC of arylmethylidene. The structures of the products were characterized thoroughly by IR, elemental analysis, MS, and NMR analysis.

The 1,3-dipolar cycloaddition of an azomethine ylide generated by a decarboxylative route from sarcosine and isatin to 1-benzyl-3,5-diarylmethylidene-piperidin-4-ones afforded novel di-spiro-indolo/pyrrolidino/piperidines in moderate yields. Further cycloaddition of these di-spiro compounds to nitrile oxide afforded tri-spiro-indolo/pyrrolidino/piperadino/isoxazolines in moderate yields with high regio- and stereoselectivity.

A new class of N1-substituted 1,2,3,6-tetrahydropyrimidin-2-ones was prepared in moderate yields by the reaction of nitrile oxide with thiazolo[3,2-a]pyrimidine derivatives via a domino 1,3-dipolar cycloaddition/ring-opening/ substitution process. The structures of the products were characterized thoroughly by IR, elemental analysis, MS, NMR together with X-ray crystallographic analysis.