Sh. M. Radwan

SYNTHESIS AND SOME REACTIONS OF THIENO[2,3-c]PYRIDAZINE DERIVATIVES AND THEIR ANTIBACTERIAL ACTIVITY

Abstract The title compounds (4a-f) were prepared by S-alkylation of 4-cyano-5,6-difur-2′-yl-2H-pyridazine-3-thione (2) and subsequent cyclization in ethanol in the presence of potassium carbonate. Reaction of o-disubstituted thienopyridazines (4a-d) with different reagents afforded tricyclic compounds namely, imidazothienopyridazine (5), pyridazinothienooxazine (6) and pyridazinothienopyrimidines (7–9). Most of the prepared compounds exhibited pronounced antibacterial activity.

Synthesis of Some Pyridothienopyrazolopyrimidopyrimidine and Mercaptomethylpyrazolopyrimidine Derivatives

Mercaptomethylpyrazolopyrimidine (2) was synthesized and reacted with ethyl chloroacetate to afford ethyl pyrazolpyrimidinylmethylmercapto acetate ( 3) , which in turn was converted into the corresponding carbohydrazide 4 . Carbohydrazide 4 reacts with a variety of reagents to give different pyrazolopyrimidines ( 5–12 ). Chloromethyl-pyrazolopyrimidine (1) reacts with chloropyridine to give compound 13 , which was subjected in a series of reactions to give new compounds 14–20 .

Synthesis of Pyrrolo[1′,2′:1′,2′]Pyrazino-[6′,5′:4,5]Thieno[2,3-c]Pyridazine Derivatives and Related Pentacyclic Heterocycles

Abstract Ethyl-5-amino-3,4-diphenylthieno[2,3-c]pyridazine-6-carboxylate(1) was converted into ethyl 3,4-diphenyl-5-(1-pyrrolyl)-thieno[2,3-c]pyridazine-6-carboxylate(2). Several derivatives of the latter compound have been synthesized. Also, the synthesis of 3,4-diphenylpyrrolo[1″,2″:1′,2′]pyrazino[6′,5′:4,5]-thieno[2,3-c]pyridazines and other related fused heterocycles are described.

Synthesis and anti-microbial activity of some imidazo[1', 2' :5,6]pyrimido[4,5-c]pyridazines and related heterocycles

The synthesis of the title heterocycles was achieved using 3-amino-5,6-diphenylpyridazine-4-carbonitrile (4) as a starting material. This compound was converted into the corresponding 4-imidazolinyl derivative 5 which was then subjected to cyclization reactions to afford the title compounds.

SYNTHESIS OF PYRIDAZOTHIENOTHIAZINE AND PYRIMIDOTHIENOPYRIDAZINES

Abstract 3-amino-4,5-diphenylthieno[2,3-c]pyridazine-2-arylcarboxamide 2 underwent cyclization with triethyl orthoformate and with nitrous acid to give the pyrimidothienopyridazines 3a-c, 4b respectively. 3-amino-4,5-diphenylthieno[2,3-c] pyridazine-2-carbohydrazide 6 reacted with aromatic aldehydes to give the corresponding carbohydrazones 7a-c. Compound 7 reacts with triethyl orthoformate, acetic anhydride or with CS2/pyridine to produce pyrimidothienopyridazines 8,9 and pyridazothienothiazine 11.

Liquid crystalline polymers VIII: thermotropic liquid crystalline poly(hydrazone–ether)s containing bis-thiophene linked to the main chain through spacers of various lengths

A new series of poly(hydrazone–ether)s was synthesized from 3,4-dimethylthieno [2,3-b] thiophene-2, 5-dicarbohydrazide, II and 4,4′-diformyl-α, ω-diphenoxyalkanes or 4,4′-diformyl -2,2′-dimethoxy -α, ω-diphenoxyalkanes. The inherent viscosities of the polymers were in the range 0.22 – 0.56 dIg−1. Majority of the polymers were soluble in concentrated H2SO4. Their thermotropic liquid crystalline properties were examined by DSC, an optical polarizing microscopy using a hot stage and thermogravimetric analyses. The polymers exhibited almost thermotropic liquid crystalline properties. In most cases, the mesophases extended up to 430°C, where thermal decomposition prevented further observation.

PYRIDAZINE DERIVATIVES: SOME REACTIONS OF 5-AMINOTHIENO[2,3-c]PYRIDAZINE-6-CARBONITRILES, SYNTHESIS OF NEW CONDENSED PYRIMIDO AND TRIAZINOTHIENOPYRIDAZINES

Abstract 3.4-Difuryl or 3,4-diphenyl-5-aminothieno[2,3-c]pyridazine-6-carbonitriles 2a,b were prepared and subjected to some sequence reactions to afford new condensed polycyclic compounds containing thieno[2,3-c]-pyridazines with anticipated biological activity.

SYNTHESIS AND REACTIONS OF SOME NEW HETEROCYCLIC COMPOUNDS CONTAINING THIENO[2,3-c] PYRIDAZINE MOIETY

Abstract Saponification of ethyl 3-amino-4,5-diphenylthieno[2,3-c]pyridazine-2-carboxyate (1) with alcoholic sodium hydroxide, followed by acidification, afforded the corresponding acid 2. Also, reaction of 1 with ethanolamine and formamide, respectively, gave compounds 5 and 6. Compound 2 reacts with orthophosphoric acid under different conditions to give some new thieno[2,3-c] pyridazine derivatives 3 and 4, which were subjected to reactions to produce compounds 7–18. Furtheremore, compounds 5 and 6 were used to synthesize some substituted pyrimid0[4′,5′:4,5]-thieno[2,3-c]pyridazine derivatives 21–30.

SYNTHESIS OF DIARYLSULPHIDES AND DIARYLSULPHONES CONTAINING PYRAZOLINE, ISOXAZOLINE, PYRIMIDINE AND CONDENSED PYRIDAZINE MOIETIES

Abstract Arylhydrazones 2a-c obtained by the reaction of diazotized 4-amino-4′-nitrodiaryi sulphide (1) with active methylene compounds i.e. ethyl acetoacetate, acetylacetone and diethyl malonate are condensed with hydrazines, hydroxylamine, urea and thiourea to give the corresponding pyrazolines (3, 4, 8, 9, 13), isoxazolines (5, 10) and pyrimidines (6, 7, 11, 12, 14, 15). Intramolecular cyclization of arylhydrazones 2a, c with AlCl3 in chlorobenzene yielded the cinnoline derivatives (16, 17). Reaction of cinnoline derivative (16) with hydrazines afforded the corresponding pyrazolo[4,3-c]cinnoline derivatives (18, 19). Oxidation of some of the prepared sulphides with H2O2/AcOH at room temperature gave the corresponding sulphones (20-30).