H. Abdel-Rahman

Preparation of new polycyclic compounds derived from benzofurans and furochromones. An approach to novel 1,2,3-thia-, and selena-diazolofurochromones of anticipated antitumor activities

Base catalyzed condensation of enaminoketones (3a,b) with malononitrile yields the respective 7-imino-5[2(substituted)prop-1-enyl]furochromene-6-carbonitriles (4a-d) according to the nature of base used. Compounds (3a, b) condense also with indan-1,3-diketone (5) to give α, β-unsaturated carbonyl compounds (6a) and (6b), respectively. Pyrrolidine-catalyzed condensation of visnaginone (2a) and khellinone (2b) with active methylenes yields the corresponding 1-[7,7-(substituted) furobenzodihydropyrone derivatives (7a-e) which condense with semicarbazide to give the respective semicarbazones (8a-e). Compounds (8b,e) react with thionyl chloride to give the respective 1,2,3-thiadiazoles (9a,b) meanwhile compounds (8a-e) react also with selenium dioxide to give 1,2,3-selenadiazoles (9c-g), respectively. Chalcones (11a,b) were obtained upon condensing (2a,b) with ferrocene-2-carboxaldehyde (10). Compatible elementary and spectroscopic measurements were in good accord with the structures postulated for the new compounds. The antitumor activities of certain selected new compounds were screened, in vitro, against a panel of four (breast: MCF-7, cervix: HELA, colon: HCT116 and liver: HEPG2) human solid tumor cell lines and the structure activity relationship (SAR) was discussed.

Synthesis and antitumor studies of novel benzopyrano-1,2,3-selenadiazole and spiro[benzopyrano]-1,3,4-thiadiazoline derivatives

A convenient and efficient synthetic protocol of new selenadiazole and thiadiazoline derivatives incorporating benzopyranone moiety from readily available starting materials was described. Reaction of different 2,2-dialkyl and 2,2-spirocycloalkyl dihydrobenzopyranones 1a–e with semicarbazide hydrochloride and thiosemicarbazide afforded the corresponding semicarbazones 2a–e and thiosemicarbazones 3a–e, respectively. Furthermore, cyclization of the semicarbazones 2a–e via oxidation using selenium dioxide gave a novel series of chromenoselenadiazoles 4a–e. A series of spirobenzopyrano-1,3,4-thiadidazolines 5a–e were synthesized by refluxing of the thiosemicarbazones 3a–e in acetic anhydride. The synthesized compounds were tested in vitro against four cancer cell lines namely: MCF-7, VERO, WI-38, and HEPG-2. In vivo studies were also performed using Ehrlich ascites carcinoma for antitumor activity. Interestingly, Compounds 4b and 5a showed significant antitumor activities and were capable to improve the hematological parameters as well as increase the mean survival time of the mice bearing tumor.

Synthesis and Reactions of Some New Quinoline Thiosemicarbazide Derivatives of Potential Biological Activity

Quinoline-2-carbohydrazide (3) was reacted with aryl or alkyl isothiocyanates to give the corresponding quinoline thiosemicarbazides (4a–e). Cyclization of the substituted thiosemicarbazides with sodium hydroxide led to the formation of 5-(quinolin-2-yl)-2H-1, 2, 4-triazole-3(4H)-thiones (5a–e). Desulfurization of thiosemicarbazides by mercuric oxide gave 5-(quinolin-2-yl)-1, 3, 4-oxadiazol- 2-amines (6a–e). Treatment of thiosemicarbazides with ethyl bromoacetate or α -bromopropionic acid yielded (Z)-N′-(3-substituted thiazolidin-4-oxo-2-ylidene) quinoline-2-carbohydrazides (7a–d), (8a–d), respectively. Treatment of thiosemicarbazides with chloroacetone furnished (Z)-N′-(4-methyl-3-substituted-thiazol-2(3H)-ylidene) quinoline-2-carbohydrazides (9a–d). Furthermore, the reaction of thiosemicarbazides with phosphorus oxychloride gave N-substituted-5-(quinolin-2-yl)-1,3,4-thiadiazol-2-amines (10a–e). All newly synthesized compounds were tested and evaluated for antimicrobial activity.

SYNTHESIS OF BENZO[1,2-b: 5,4-b′]- DIFURANYL-TRIAZOLES, -OXADIAZOLES, -THIAZOLIDINONES, -THIADIAZOLES, AND THE USE OF DNA IN EVALUATION OF THEIR BIOLOGICAL ACTIVITY

Benzo[1,2-b:5,4-b′]difuran-2-carbohydrazides 5a, b were reacted with aryl or alkyl isothiocyanates to give the corresponding thiosemicarbazides 6a–h. Cyclization of the substituted thiosemicarbazides with sodium hydroxide led to the formation of benzo[1,2-b:5,4-b′]difuranyl-1,3,4-triazoles 7a–f. Desulfurization of thiosemicarbazides by mercuric oxide gave benzo[1,2-b:5,4-b′]difuranyl-1,3,4-oxadiazoles 8a–f. Treatment of thiosemicarbazides with ethyl bromoacetate or α-bromopropionic acid yielded benzo[1,2-b:5,4-b′]difuranyl-carbonyl-hydrazono-4-thiazolidinones 9a–f and 10a–f, respectively. Furthermore, the reaction of the thiosemicarbazides with phosphorus oxychloride gave benzo[1,2-b:5,4-b′]difuranyl-1,3,4-thiadiazoles 11a–f. Some compounds in this study were biologically evaluated for their ability to bind to DNA.

Synthesis of Triazolyl-Oxadiazolyl-Thiazolyl- and Thiadiazolylbenzofuran of Potential Biological Activity

4,7-Dimethoxy ( Ia ) and 4-methoxy ( Ib ) 6-hydroxybenzofuran-5-carbohydrazide were reacted with aryl or alkyl isothiocyanates to give the corresponding thiosemicarbazides ( IIa-h ). Cyclization of the substituted thiosemicarbazides with sodium hydroxide led to the formation of 1,3,4-triazol-2-yl-benzofuran derivatives ( IIIa-d ). Desulfurization of thiosemicarbazide by mercuric oxide gave 1,3,4-oxadiazolyl-benzofuran ( IVa-c ). Treatment of thiosemicarbazide with ethyl bromo-acetate or f -bromopropionic acid yielded 4-thiazolidin-2-yl-carbonyl-benzofuran ( Va-h ). The reaction of compounds IIb , e , f with sulphuric acid or phosphorus oxychloride gave 1,3,4-thiadiazol-2-yl-benzofuran ( VIa-d , VII ).

Linearly Fused Furochromones by Intramolecular Enaminone Reactions

A number of new linearly fused furochromones were synthesized. The methodology was performed starting from naturally occurring visnagin and khellin via enaminone formation using N,N-dimethyl formamide dimethylacetal followed by ring closure in acidic medium. Various reactions on the enaminone derivatives are described.

Synthesis of Some New Naphthopyran, Pyrazole, Pyridine, and Thienobenzochromene Derivatives Using 1-(1-Hydroxy-2-naphthyl) Ethanone as a Versatile Starting Material

Treatment of the enaminone 2 , prepared from 1-(1-hydroxy-2-naphthyl)ethanone 1 and N,N-dimethylformamide dimethylacetal with acetic acid, thionyl chloride, or bromine, gave the corresponding 4-oxo-4H-naphtho[1,2-b]pyran derivatives 3, 4, and 5 . Refluxing of p-toluidine or p-anisidine with 2 afforded compounds 6 and 7 , respectively. The naphtho[1,2-b]pyran-3-carbaldehyde 9 was prepared via the acetylation of 2 . Condensation of 9 with malononitrile or ethyl cyanoacetate gave the pyridine derivatives 10 and 11 . Refluxing of 9 with hydrazine hydrate, phenylhydrazine, semicarbazide hydrochloride, or thiosemicarbazide afforded the pyrazole derivatives 12, 13, 14 , and 15 respectively. Reaction of ethanone 1 with malononitrile gave the chromene carbonitrile derivative 16 . Treatment of 16 with malononitrile afforded the chromene malononitrile derivative 17 . Also, compound 17 was obtained from the reaction of 1 with excess of malononitrile and catalytic piperidine. Treatment of 16 with ethyl cyanoacetate produced compound 18 . When 16 was treated with elemental sulfur, theino[3,4-c]benzochromene derivative 19 was produced. Hydrolysis of 16 with hydrochloric acid yielded the benzochromene carbonitrile derivative 20 which on heating with elemental sulfur afforded the theinobenzochromene derivative 21 . Treatment of 21 with acetic anhydride, p-chlorobenzaldehyde, phenyl isothiocyanate, or thionylchloride furnished compounds 22, 23, 24 , and 25 , respectively.

Synthesis, biological evaluation and in silico molecular docking of novel 1-hydroxy-naphthyl substituted heterocycles

Graphical abstract Novel 1-hydroxy-naphthyl substituted heterocycles were synthesized and tested in vitro as antioxidant and antimicrobial agents. In silico molecular docking were performed in order to understand the binding interactions of the molecules with the receptors.

Mannich Bases as Synthetic Intermediates: Convenient Synthesis of Functionalized 1,2,4-Triazepines, 1,4-Diazepines and 1,5-Diazocines

Transamination between the ketonic Mannich bases 1a, b and primary arylamines gave a series of ketonic sec-Mannich bases 2a - h. A variety of tetrahydro-1,2,4-triazepines 3a - f have been synthesized by treating the arylhydrazones of 2 with formaldehyde. A similar reaction with the benzenesulfonylhydrazone of 2b afforded 4. The 3-styryl-2H-1,2,4-triazepine 5 was obtained from the phenylhydrazone of 2a and cinnamaldehyde. Treatment of arylhydrazones of the 4-methoxystyryl keto base 7 with formaldehyde and cinnamaldehyde afforded the 3,4,5,6-tetrahydro-2H-1,2,4-triazepines 8a, b. Mannich reaction with 4-(p-hydroxyphenyl)-tetrahydro-1,2,4-triazepine 3d afforded the Mannich bases 9, 10 and 11. The reaction of 1b with o-phenylenediamine leads to the 1,5-benzodiazepine 13. The new tetrahydro- 1,4-diazepine and tetrahydro-1,5-diazocine Mannich bases 15 and 17 were obtained from 1b and ethylenediamine or 1,3-diaminopropane, respectively. The bi(piperidine) derivative 19 was obtained from 1a and 1,3-diaminopropane. Graphical Abstract Mannich Bases as Synthetic Intermediates: Convenient Synthesis of Functionalized 1,2,4-Triazepines, 1,4-Diazepines and 1,5-Diazocines

Synthesis of Some Chromanone Derivatives and the Use of DNA in Evaluation of their Biological Activity

Abstract 6-Formyl-7-hydroxy-5-methoxy-2-pentamethylenechromanone (2) was prepared from the naturally occurring “Visnagin” and condensed with benzil, o-phenylenediamine and 3,4-diaminobenzophenone to give the corresponding imidazolylchromanone derivatives 3-5. Knoevenagel reaction of compound 2 with different active methylene compounds afforded benzodipyranone derivatives 12a - c which may be considered as analogues to the naturally occurring “Xanthyletin and Graveolone Compounds”. The structural formula of the new compounds were established by using different methods for their preparation in addition to the instrumental analyses. Some compounds in this study were biologically evaluated for their ability to bind to DNA.