M. A. Zahran

A novel synthesis of dibenzo[c, f]chromenes, dibenzo[c, h]chromenes and benzo[7,8]chromeno[3,4-f]isoindoles as antimicrobial agents

Naphtho[2,1-b]pyranone (3) was allowed to react with arylmethylenemalononitriles to yield 4-amino-5-oxo-2-aryl-5H-dibenzo[c,f]chromene-3-carbonitriles (4a,b); with ethyl 3,4-dichlorobenzylidene cyanoacetate to furnish dibenzo[c,f]chromene (5) and with elemental sulfur in dioxane containing piperidine to give thieno[3,4-d]naphtho[2,1-b]pyranone (6). Similarly, naphtho[1,2-b]pyranone (7) was reacted with arylmethylenemalononitriles and elemental sulfur to furnish dibenzo[c,h]chromenes (8) and thieno[3,4-d]naphtho[1,2-b]pyranone (10), respectively. Compound 10 underwent cycloaddition with N-arylmaleimides to yield benzo[7,8]chromeno[3,4-f]isoindoles (11a-c). Some of these compounds were screened in vitro for their antimicrobial activities.

Oxidation of 3-aminoquinazolinones with lead tetraacetate. A novel synthesis of naphtho-fused azirino-pyrazolo- and 1,4,5-oxadiazepino-quinazolinones

Oxidation of 3-aminoquinazolin-4(3H)-one derivative 3c using lead tetraacetate in methylene chloride at −20°C gave aziridine 4, while reaction of 7b and 7c under similar conditions gave the oxadiazepine derivatives 7H-naphtho[2′,1′:6,7][1,4,5]oxadiazepino[3,4-b]quinazolin-9(15H)-one (9) and 16H-naphtho[1′,2′:6,7][1,4,5]oxadiazepino[3,4-b]quinazolin-14(8H)-one (11), respectively.

1,4-PHENYLENEDIISOTHIOCYANATE IN THE SYNTHESIS OF BIS-(THIOUREA, BENZOTHIAZOLE, QUINAZOLINE, 1,3-BENZOXAZINE AND IMIDAZOLIDINEIMINOTHIONES) DERIVATIVES

Interaction of 1,4-phenylenediisothiocyanate 1 with aromatic amines and o-phenylenediamine furnished the novel bisthiourea derivatives 2a–c and 7. Hydrazines or o-aminothiophenol reacted with 1 to produce bis-(thiosemicarbazide 4a,b or benzothiazole 9) derivatives. Bisquinazolines 12a,b and bisthienopyrimidines 13a,b were synthesized through interaction of 1 with anthranilic acids 10a,b and aminothiophenes 11a,b. Interaction of 1 with two moles of either salicylic acid or N-(4-substituted-phenyl)cyanothioformamide yielded the corresponding bis(1,3-benzoxazine 14 or imidazolidineiminothiones 16) derivatives.

Utility of cyanothioformamides in synthesis of some bis(imidazole, oxazole, thiazole, oxadiazole, triazole, benzoxazinethione and quinazoline) derivatives

Interaction of 1,4-bis(cyanothioformamido)benzene 2 with various electrophilic and nucleophilic reagents furnished the corresponding bis(imidazole, oxazole, thiazole, oxadiazole, triazole, benzoxazinethione and quinazoline) derivatives.

SOME REACTIONS WITH 6-BENZOYL-3-AMINO-2-IMINO-2,3- DIHYDROTHIAZOLO[4,5-b]QUINOXALINE: SYNTHESIS OF (1,2,4) TRIAZOLO[3′,2′:2,3]THIAZOLO[4,5-b] QUINOXALINE AND (1,3,4)THIADIAZINO [5,6-b]QUINOXALINE DERIVATIVES

Abstract Condensation of 6-benzoyl-3-amino-2-imino-2,3-dihydrothiazolo[4,5-b]quinoxaline (IV) with aldehydes, formic acid and acetyl chloride yielded the corresponding Schiff bases (VI), N-formyl (VIII) and triacetyl (IX) derivatives, respectively. While, interaction of (IV) with benzoyl chloride and ethyl cyanoacetate produced the (1,2,4) triazolo[3′,2′:3,2] thiazolo[4,5-b]quinoxaline derivatives (X) and (XI), respectively. Also, interaction of (IV) with carbon disulphide caused ring expansion to give (1,3,4) thiadiazino[5,6-b]quinoxaline (XII) and (XV) was also prepared in one pot reaction on condensation of 6-benzoyl-2,3-dichloro-quinoxaline with thiocarbohydrazide.

New 1,3-diaryl-5-thioxo-imidazolidin-2,4-dione derivatives: synthesis, reactions and evaluation of antibacterial and antifungal activities

Abstract New cyanothioformamide derivative 1 was prepared by treatment of 3,5-dichlorophenyl isothiocyanate with potassium cyanide at room temperature. Cycloaddition of cyanothioformamide 1 with phenyl isocyanate as electrophile furnished the corresponding imidazolidine 2. Imine hydrolysis of 2 with ethanolic HCl produced the corresponding 4-thioxo-2,5-imidazolidinedione 3. This compound was used as key synthon for the preparation of a wide variety of new substituted imidazole compounds. Condensation of 3 with different types of hydrazine derivatives furnished new series of hydrazone 4a, b, thiosemicarbazone 5a, b and cyanoacetohydrazide 6 derivatives incorporating imidazolidine moiety. Finally, cyanoacetohydrazide 6 was used as intermediate for synthesizing new compounds. Evaluation of the antibacterial and antifungal activities for the synthesized compounds was carried out to probe their activities. Most of the tested compounds showed significant activities. The dione derivative 3 and the imidazolidine derivative 9a, which incorporates a chromene moiety, exhibited high activity near the reference drug against all tested organisms.