Mei-Hsiu Shih

Studies on the syntheses of heterocycles from 3-arylsydnone-4-carbohydroximic acid chlorides with N-arylmaleimides, [1,4]naphthoquinone and aromatic amines

Abstract 3-Arylsydnone-4-carbohydroximic acid chlorides ( 1 ) could react with N-arylmaleimides ( 3a–b ) or 2-methyl-N-phenylmale-imide ( 3c ) to give 3-(3-arylsydnon-4-yl)-5-aryl-3a,6a-dihydro-pyrrolo[3,4-d]isoxazole-4,6-diones ( 4a–h ) or 6a-methyl-3-(3-arylsydnon-4-yl)-5-phenyl-3a,6a-dihydro-pyrrolo[3,4-d]isoxazole-4,6-diones ( 4i–l ), respectively. However, 3-(arylsydnon-4-yl)-naphtho[2,3-d]isoxazole-4,9-diones ( 6a–d ) were obtained in good yield by the reaction of carbohydroximic acid chlorides 1 with [1,4]naphthoquinone. Furthermore, 2-(3-arylsydnon-4-yl)benzoxazoles ( 9a–d ) and 2-(3-arylsydnon-4-yl)benzothiazoles ( 9e–h ) were obtained via the reaction of carbohydroximic acid chlorides 1 with ortho-substituted aromatic amines 7a and b .

Access to the syntheses of sydnonyl-substituted α, β-unsaturated ketones and 1,3-dihydro-indol-2-ones by modified knoevenagel reaction

Abstract A convenient method for the preparation of sydnonyl-substituted α, β-unsaturated ketones, based on Knoevenagel condensation, is presented. Although well known, this reaction has never been utilized in the condensation involving sydnone derivatives. Thus, 3-aryl-4-formylsydnones ( 1 ) are reacted with active methylene compounds such as acetylacetone ( 2a ), ethyl acetoacetate ( 2b ), diethyl malonate ( 2c ), malononitrile ( 4a ), ethyl cyanoacetate ( 4b ) and cyanoacetamide ( 4c ) by modified Knoevenagel condensation to afford multifunctional derivatives. Also, sydnonyl-substituted 1,3-dihydro-indol-2-one derivatives 10 were synthesized successfully by condensing 3-aryl-4-formylsydnones ( 1 ) with oxindoles 9 .

Novel synthesis of palladium (II) complexes derived from 3‐arylsydnone‐4‐carbaldehyde N(4)‐phenylthiosemicarbazones and biological activity

The aim of this research is to investigate whether the oxygen atom O(6) in the sydnone ring of 3‐arylsydnone‐4‐carbaldehyde N(4)‐phenylthiosemicarbazones (HArSYTSCs, 3a–d) is a good electron donor atom upon metal complexation. Furthermore, ligands 3a–d and the corresponding palladium complexes (Pd(ArSYTSC)Cl, 4a–d) would be expected to find their potent biological activities.

A facile synthesis and antimicrobial activity evaluation of sydnonyl-substituted thiazolidine derivatives.

Some new sydnonyl-substituted thiazolidine derivatives were synthesized in high yields by the modified Knoevenagel condensation of 3-aryl-4-formylsydnones with thiazolidine-2,4-dione and 2-thioxo-thiazolidine-4-one, respectively. All the synthesized thiazolidine derivatives were screened by paper-disc method to identify their antimicrobial activities against three bacteria viz. Staphylococcus aureus, Proteus vulgaris and Escherichia coli, and two fungal cultures viz. Aspergillus niger and Penicillium citrinum. The reference drugs were Norfloxacin and Griseofulvin, respectively. The screening data indicated that the tested sydnonyl-substituted thiazolidine derivatives exhibited no obvious antibacterial activity compared with the standard drug Norfloxacin. However, thiazolidine derivatives displayed significant antifungal activities against Penicillium citrinum and Aspergillus niger. Notably, all of the tested compounds showed growth inhibitory activity 1.5-4.4 times higher than that of the standard drug Griseofulvin against the two fungi.

Syntheses of Nickel (II) Complexes from Novel Semicarbazone Ligands with Chloroformylarylhydrazine, Benzimidazole and Salicylaldehyde Moieties

This study addressed the design and syntheses of diverse ligands, which were then successfully treated with Ni (II) ion to afford a series of nickel complexes. α-Chloroformylarylhydrazine hydrochlorides 6 contain two different functional groups. One is a strong nucleophile, and the other is a good electrophile. Therefore, it can be designed to react with several reagents to obtain diverse derivatives which can be used as ligands for metal complexes. Furthermore, benzimidazole and salicylaldehyde can provide electron donor sites, N and O electron donors, separately. Hence, the starting materials α-chloroformylarylhydrazine hydrochlorides 6 were first treated with 2-(aminomethyl)-benzimidazole (7) to give the corresponding semicarbazides 8. Then, the semicarbazides 8 reacted with various substituted salicylaldehydes 9–11 to afford the desired substituted-salicylaldehyde 2-aryl-4-substituted semicarbazones 12–14, which could coordinate with nickel (II) ion to give the corresponding nickel complexes 15–17.