A. A. O. Sarhan

One pot synthesis of novel thiazolo[3,2-b][1,2,4]triazoles: A useful synthetic application of the acidified acetic acid method

Thiazolo[3,2-b][1,2,4]triazoles and some of its analogues were firstly synthesized starting from 3-benzyl-1,2,4-triazole-5-thiol (13). 3-Benzyl-1,2,4-triazole-5-thiol (13) was synthesized and reacted with aromatic ketones using the acidified acetic acid method (AcOH/H+) to give directly the cyclized 5-aryl-2-benzyl-1,3-thiazolo[3,2-b][1,2,4]triazoles (15a-f) rather the thioketones 14. The isomeric 2-benzyl[2,3-c]-1,2,4-triazoles 16 could not be obtained using this method. The reaction of 1-phenylacetyl-3-thiosemicarbazide (17) with phenyl bromomethyl ketones in refluxing ethanol afforded the 2-(phenylacetyl-hydrazino)-4-phenylthiazole (18) which, cyclized into 16a upon refluxing in POCl3. The tricyclic system 20a–d was successfully prepared in one pot reaction using the acidified acetic acid in high reaction yield and short reaction time. Formation of both 15a–l and or 16a–c was assigned by the molecular minimization energy (MME) calculations which indicated that the formation of 15 is more favorable than the isomeric compounds 16. Examination of the biological activity against the selected bacteria and fungi revealed that the title compounds possess significant growth promoting effect.

Synthesis and Studies of Triazolothiadiazines. An Approach Toward New Biologically Active Heterocyclic Compounds

The first synthesis of the 1,2,4-triazolo[5,1-b][1,3,5] thiadiazine and some of its analogues, possessing a thiadiazino-s-triazole bicyclic ring system was performed starting from 2-benzyltriazole-5-thiol. The title compounds 6a–g were synthesized via double Mannich reaction in one step in high yields. The route employed the nucleophilic addition of two moles of CH 2 O onto the NH and SH groups of the triazole ring followed by cyclocondensation with elimination of two H 2 O molecules to form the thiadiazine derivatives. Examination of the biological activity against the selected fungi and bacteria is the main goal of this article. The tested compounds against fungi revealed that the title compounds were active against most strains of fungi, while the tested compounds were inactive against Gram +Ve and Gram –Ve bacteria. All new synthesized compounds were confirmed using the spectral analyses and the direction of the cyclization was confirmed using the molecular mechanics calculations.

The rearrangement of 11,13-dibromo-9,10-dimethoxy-9,10-propanoanthracen-12-ones to the correspondingFavorskii products

SummarySubmittingcis- andtrans-11,13-dibromo-9,10-dimethoxy-9,10-propanoanthracen-12-one (4a,b) toFavorskii conditions (MeOH/KOH, 60°C) afforded theFavorskii ester5a and the α-keto acetal5b in 46% overall yield. Almost all reactions resulted in the formation of a single isomer which could be shown to be the most favored one by molecular mechanics calculations (MM2).ZusammenfassungUnterFavorskii-Bedingungen (MeOH/KOH, 60°C) entstehen auscis- undtrans-11,13-Dibrom-9,10-dimethoxy-9,10-propanoanthracen-12-on derFavorskii-Ester5a und das α-Keto-Acetal5b in 46% Gesamtausbeute. Fast alle Reaktionen ergeben ein einziges Isomeres, von dem mittels molekularmechanischer Berechnungen gezeigt werden konnte, daß es sich dabei um das energetisch günstigere Produkt handelt.

Synthesis and reactions of new 4-chloro-2-methylpyrimidino[4′,5′:4,5]thiazolo[3,2-a]-benzimidazoles

Summary4-Chloro-2-methylpyrimidino[4′,5′:4,5]thiazolo[3,2-a]benzimidazole (3) was prepared by chlorination of2 which could also be converted directly to 2-methylpyrimidino[4′,5′:4,5]-thiazolo[3,2-a]benzimidazol-4-thiol (4). Nucleophilic substitution of3 with alcohols, phenols, primary amines, secondary amines, sodium azide, and mercaptoacetic acid gave the corresponding derivatives. The thiol derivative4 was reacted with alkyl/aralkyl halides, phenacyl bromide derivatives, bromoacetone, chloroanilides, bromomalonic ester, and ethyl bromoacetate to afford compounds of potential pharmacological interest.Zusammenfassung4-Chlor-2-methylpyrimidino[4′,5′:4,5]thiazolo[3,2-a]benzimidazol (3) wurde durch Chlorierung von2, welches auch direkt zu 2-Methylpyrimidino[4′,5′:5,4]thiazolo[3,2-a]-benzimidazol-4-thiol (4) umgesetzt werden kann, hergestellt. Nucleophile Substitution von3 mit Alkoholen, Phenolen, primären Aminen, sekundären Aminen, Natriumazid und Mercaptoessigsäure ergab die entsprechenden Derivate. Das Thiolderivat4 wurde mit Alkyl/Alkarylhalogeniden, Phenacylbromidderivaten, Bromaceton, Chloraniliden, Brommalonsäureester und Bromessigsäureethylester zu potentiell pharmakologisch interessanten Verbindungen umgesetzt.

Reactions and Reactivity of Thienopyridines: Facile Synthesis of Some Pyridothienooxazepine Derivatives

Pyridothienooxazepines were synthesized by the interaction salt of the 3-aminothienopyridine-2-carboxylate with activated α-haloketones or α-halonitriles. Several derivatives of thienopyridine were prepared either by the replacement of an amino group or by using an amino group in 3-aminothienopyridine-2-carboxylate to synthesize another derivative of thienopyridine.

Synthesis and redox behavior of new ferrocene-π-extended-dithiafulvalenes: An approach for anticipated organic conductors

Summary A number of new ferrocene-π-extended-dithiafulvalenes were successfully synthesized as new electron donor compounds. The chemical structures and electrochemical behaviors of these compounds were investigated using several spectroscopic methods. The synthesis of these compounds was achieved using the modified Wittig–Horner cross-coupling reaction using n-BuLi/THF at temperature varies from −78 °C to 0 °C. These new classes of bis(1,3-dithiafulvalene)ferrocenes have the 1,3-dithiole ring system separated by ferrocene as conjugated spacer. The ferrocene-dithiafulvalenes derivatives 9 and 12 were prepared as side products during the synthesis of the targeted compounds as bis(1,3-dithiafulvalene)ferrocenes 8, 10 and 11 in variable yields. The redox properties of the compounds have been investigated by cyclic voltammetry at ambient temperature using tetra-n-butylammonium perchlorate (TBAP) as the supporting electrolyte compared to ferrocene and the derivative 9. In CH2Cl2 on a Pt working electrode and at ambient temperature, two oxidation waves associated with two reduction waves at scan rates 100 mV s−1 were observed for 9 and 12. In contrast the anodic peak potential of bis(1,3-dithiafulvalene)ferrocenes 8, 10 and 11 exhibited two and three oxidation waves associated with two reduction waves.