Michael Addition Of Compounds Research Articles

A facile approach for synthesis of thiazines-, thiazoles- and triazoles-annulated 6-styryl-2-thiouracil derivative

Utility of 4-oxo-6-styryl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carbonitrile 1 in synthesis of a new series of fused pyrimidines was described. Pyrimido[2,1-b][1,3]thiazines 6–9 were obtained via Michael addition of compound 1 to the polarized systems 2–5 in the presence of nanosized ZnO. S-alkylation of pyrimidine 1 followed by cyclization with phenacyl bromide, monochloroacetic acid, chloroacetonitrile and oxalyl chloride afforded the desired thiazolo[3,2-a]pyrimidines 10–13. Hydrazinolysis of compound 1 followed by addition cyclization with acetic anhydride, formic acid, carbon disulfide and benzoyl chloride afforded triazolo[4,3-a]pyrimidines 15–18. The antimicrobial screening showed high activity for thiazolo[3,2-a]pyrimidines 11 and 12 against both Gram (+ ve) and Gram (− ve) bacteria.

Synthesis and evaluation of some new oxazolones and imidazolones as antioxidant additives for Egyptian lubricating oils

Oxazolone derivative 2 was utilized as a key intermediate for synthesis of some new oxazolone and imidazolone derivatives. Reaction of oxazolone derivative 2 with diamines under different conditions afforded the corresponding imidazolone derivatives 3–8, respectively. Moreover, oxazolone 2 reacted with some heterocyclic amines in glacial acetic acid giving the corresponding imidazolone derivatives 9–14, respectively. Cyclocondensation of thiosemicarbazide with compound 2 in dry pyridine afforded compound 15. Addition of secondary amines to olefin double bond of compound 2 gave the corresponding addition products 16–19, respectively. Michael addition of compound 2 with some active methylene compounds afforded oxazolone derivatives 20–23, respectively. These prepared products were evaluated as antioxidant and corrosion inhibitors for gasoline lubricating oil and compounds 6a–c, 10 and 15 exhibited the highest antioxidant and anticorrosive activities. The effect of concentration of additives was studied to recommend the optimum concentration to be used. The results showed, for additive 15, 0.1 g for 1 L oil was the more effective concentration. Measurements for thermal analysis and of surface tension of oil after oxidation were also carried out.

Synthesis, characterization of some benzazoles bearing pyridine moiety: Search for novel anticancer agents

Thirteen novel benzazole derivatives were synthesized as possible anticancer agents. The first intermediate 1,3-benzothiazol-2-ylacetonitrile ( 2) was synthesized via cyclodeamination reaction of o-aminothiophenol ( 1) with malononitrile. Also, the second intermediate 5,6-dimethyl-1 H-benzimidazol-2-ylacetonitrile ( 10) was afforded via cyclocondensation reaction between 4,5-dimethyl-1,2-phenylenediamine ( 9) and ethylcyanoacetate. Nucleophilic reaction of benzimidazolyl NH of compound ( 10) with ethylcyanoacetate afforded benzimidazolyl-3-oxopropanenitrile ( 11). On the other hand, methylenation of CH 2 function of compound ( 10) with dimethylformamide/dimethylacetal afforded benzimidazolylprop-2-enenitrile 12. The synthesis of benzothiazoylpyridines 5a, b and 8a, b as well as benzimidazolylpyridines, 14a, b and 17a– d was carried out through Michael addition of compounds 2 or 10 with arylidenemalononitriles 3a, b and 4a– d. The combination of pharmacophoric anticancer moieties, pyridine and benzazoles was the base on which target compounds 5a, b, 8a, b, 14a, b and 17a– d were designed. Among the synthesized compounds, four derivatives 10 and 17b– d were selected by National Cancer Institute (NCI), USA to be screened for their anticancer activity at a single high dose (10 −5 M) against a panel of 60 cancer cell lines. Compound 17b 4-[ p-chlorophenyl]pyridine and 17d 4-[ p- methoxyphenyl] pyridine exhibited a broad and moderate antitumor activity against 41 tumor cell lines belonging to the nine subpanels employed and are selected for further evaluation at five dose level screening.

N-aryl-2-hydroxy-1,2,3,4-tetrahydropyridines and N-aryl-2-chloromethylene-1,2,3,4-tetrahydropyridines — successive intermediates in the Hantzsch synthesis of 1,4-dihydropyridines

Esters of 4-chloro-2-arylideneacetoacetic acid I and esters of N-arylaminocrotonic acid II form stable N-aryl-3,4-trans-2-hydroxy-1,2,3,4-tetrahydropyridines III. Their regio- and stereoselective dehydration results in N-aryl-2-chloromethylene-1,2,3,4-tetrahydropyridines with an exocyclic bond, IV. Compounds IV isomerize to the corresponding N-aryl-2-chloromethyl-1,4-dihydropyridines V in acid medium. Michael addition of compounds I and II in chloroform or benzene forms carbocyclic derivatives of cyclohexene VI.