Regioselectivity in Reactions of Bis‐Hydrazonoyl Halides with Some Bifunctional Heterocycles

Bis‐hydrazonoyl chloride 1 reacts regioselectively with 3‐mercapto‐1,2,4‐triazole 2a , 2,3‐dihydro‐3‐thioxo‐1,2,4‐triazin‐5(4H)‐one 2b and 2‐mercaptobenzimidazole 2c to give the hitherto unknown annelated 2,3‐bis‐(phenylhydrazono)thiazoles 6a‐c , respectively. Reactions of 1 with the methylthio derivatives of such heterocycles afforded the annelated 3,3′‐bis‐(1,2,4‐triazoles) 11a‐c , respectively. Similar reaction of 1 with 2‐phenylamino‐4(3H)‐pyrimidinones 4 gave 2,3‐bis(phenylhydrazono)imidazo[1,2‐a]pyrimidin‐5(1H)‐ones 16 . Oxidation of 6c yielded the corresponding bis(phenylazo) derivative 15 . The regiochemistry of the studied reactions is discussed.     

Convenient Synthesis of Functionalized Bis‐ureidopyrimidinones Based on Thiol‐yne Reaction

The preparation of functionalized bis‐ureidopyrimidinones ( Bis‐UPy ) through the thiol‐yne reaction is described. Various Bis‐UPys with different functional groups were synthesized by using the readily available functionalized alkynes and UPy‐thiol to affirm the simplicity and versatility of the methodology.     

Convenient Synthesis of Polyaza‐2‐(heteroaryl)pyridine Derivatives

A simple and efficient method for the synthesis of new heterocyclic compounds containing pyridine and 1,3‐pyrimidine units has been developed. It is based on the reaction of the appropriate enaminone with some N‐nucleophiles.     

Utility of Bis‐Hydrazonoyl Chlorides as Precursors for Synthesis of New Functionalized Bis‐Thiadiazoles as Potent Antimicrobial Agents

N′,N″‐([1,1’‐Biphenyl]‐4,4′‐diyl)bis(2‐oxopropanehydrazonoyl chloride) is considered to be the key intermediate for the synthesis of a variety bis‐1,3,4‐thiadiazole derivatives in one step methodology with good yields by reaction of with a series of hydrazinecarbodithioate derivatives 2a–e , 6a , b , and 8a–e . The assigned structures for all the newly synthesized compounds were confirmed on the basis of elemental analyses and spectral data (infrared, NMR, and mass), and the mechanisms of their formation were also discussed. Moreover, the antimicrobial activity for twelve selected products was screened, and the results obtained exploring the high potency of some of the tested compounds compared with the employed standard bactericides and fungicides. In addition, the minimum inhibitory concentration of the tested compounds was determined, and the results obtained exploring the high potency of three of the tested compounds against all the tested microorganisms.     

Synthesis of a Novel Tri‐enaminone as Building Block for Polyaza‐heterocycles

The new tri‐enaminone, namely, 3,4‐bis (3‐dimethylamino‐2‐propenoyl)‐1‐[4‐(3‐dimethylamino‐2‐propenoyl)phenyl]‐5‐methyl‐1H‐pyrazole was prepared and used as building block for synthesis of novel polyaza‐heterocycles. The latter compounds were obtained via an efficient one‐pot reaction of the tri‐enaminone with 1,3‐dipoles and various electrophilic and nucleophilic reagents. The structures of the new products were confirmed based on elemental and spectral analyses. Also, alternative synthetic methods were carried out wherever possible as further evidence for some of the newly synthesized products.     

Reactions with Hydrazonoyl Halides 611: Synthesis of 2,3-Dihydro-1,3,4-Thiadiazoles

2-[1,2-Diaza-3-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))prop-2-enylidene]-3-phenyl-5-substituted 1,3,4-thiadiazolines and 2-{[4-(2,3-dimethyl-5-oxo-1-phenyl(3-pyrazolin-4-yl))(1,3-thiazol-2-yl)]cyanomethylene}-3-phenyl-5-substitu- ted 1,3,4-thiadiazolines were synthesized from hydrazonoyl halides and 4-{-2-aza-2-[(methylthiothioxomethyl)amino]vinyl}-2,3-dimethyl-1-phenyl-3-pyrazoin-5-one and 2-[4-(2,3-dimethyl-5-oxo-1-phenyl-3-pyrazolin-4-yl)-1,3-thiazol-2-yl]ethane-nitrile, respectively. All synthesize compounds were elucidated by elemental analysis, spectra, and alternative synthesis routes, whenever possible.     

A New Sustainable Strategy for Synthesis of Novel Series of Bis‐imidazole and Bis‐1,3‐thiazine Derivatives

An expeditious, eco‐friendly, and efficacious protocol was achieved for the preparation of bis‐imidazoles and bis‐1,3‐thiazines from the reaction of tetracyanoethylene with dialdehydes or bis‐thiosemicarbazones, respectively. Merely mixing and sonicating the starting materials furnishes the desirable products in considerable yields. This reaction smoothly proceeded and presented many merits, over conventional and mechanochemical approaches, including simple experimental workup procedure, no by‐products, and short reaction time. Moreover, the protocol scoring admirably in various green metrics, as a consequence, shows these approaches to be an ideal sustainable and green process.     

Reaction with Hydrazonoyl Halides 64: Synthesis of Some New Triazolino[4,3‐a]pyrimidines, 1,3,4‐Thiadiazoles,and 5‐Arylazothiazoles

2,3‐Dihydro‐1,3,4‐thiadiazoles, 2,3‐dihydro‐1,3,4‐selenadiazoles, and triazolino[4,3‐a]pyrimidines containing benzofuran moiety were prepared from the reaction of 2‐(2‐phenylhydrazono)‐1‐(5‐bromobenzofuran‐2‐yl)‐2‐chloroethanone with each of potassium thiocyanate, potassium selenocyanate, alkyl carbodithioate, and pyrmidine‐2‐thione derivatives. All the newly synthesized compounds were confirmed by elemental analysis, spectral data, and alternative route synthesis whenever possible.     

Terephthalaldehyde: An Effecient Key Precursor for Novel Synthesis of Some Interesting Bis‐thiazoles and Bis‐triazolopyrimidinones

Novel bis‐thiazoles were synthesized in high and efficient yields from the reaction of thiosemicarbazones with halogenated compounds. Also, new bis‐triazolopyrimidines were prepared from the reaction of hydrazonoyl chlorides with bis‐thione derivative. All prepared compounds were fully characterized by spectral methods. The synthesized bis‐compounds will be attractive species for the medicinal researchers to investigate their biological activity.     

Reactions with Hydrazonoyl Halides 341: Synthesis of Some New 2,3-Dihydro-1,3,4-thiadiazoles

Hydrazonoyl halides 4a–h have been caused to react with each of alkyl carbodithioates (3, 13–17)a,b in the presence of triethylamine to give 2,3-dihydro-1,3,4-thiadiazoles in good yields. Structures of the new compounds were elucidated on the basis of elemental analyses, spectral data, and alternative methods of synthesis whenever possible.     

A Convenient Synthesis of Novel Glycosyl Azetidines Under Mitsunobu Reaction Conditions

Abstract

A facile, simple, and high-yielding protocol for synthesis of novel glycosyl azetidines was developed from glycosyl β-amino alcohols via intramolecular cyclization under Mitsunobu reaction conditions.     

Studies on Organophosphorus Compounds XI: The Reaction of Phosphorus Reagents With Hydrazonoyl Halides,Hydrazonoyl Azides,and Shiff's Bases

N-(chloro-furan-2-yl)methylene-N′-(4-nitrophenyl)hydrazone (I) reacted with triethylphosphite to produce the phosphonate derivative III. The tetrazine derivative VI was produced by the interaction of I with diethyl-phosphite. Hydrazonoyl azide derivatives VIIIa–c reacted with triphenyl phosphine to form the iminophosphorane derivatives Xa–c. On the other hand, the azide derivative VIIIc reacted with the phosphonium ylide XI to form the 1,2,3-triazole adduct XIII. The reaction of triethyl phosphite with Shiff's bases XIVa–c yielded the corresponding phosphonates XVa–c. The structures of the newly prepared compounds were confirmed with the analytical and spectroscopic evidences.     

Ultrasound Assisted Synthesis of Some Novel Bis‐Pyridazine Derivatives

Bis‐enaminone 3 was coupled with aryldiazonium chlorides 4a , 4b to afford the bis‐arylhydrazonopropanals 6a , 6b . Compounds 6a , 6b could be utilized for the synthesis of a variety of bis‐(dimethyl 2,3‐dihydropyridazine‐3,4‐dicarboxylate), bis‐(pyridazin‐3(2H)‐one), bis‐(2,3‐dihydropyridazine‐4‐carbonitrile) and bis‐(3‐imino‐2,3‐dihydropyridazine) derivatives, under ultrasonic irradiation. A comparative study of aforementioned reactions was carried out under conventional method as well as under ultrasonic irradiation conditions.     

Novel Reaction Route Including Enzymic Reaction For A Synthesis Of A Branched Polysaccharide

Abstract

Stereoselective synthesis of α-D-glucosyl-branching polysaccharide by chemical and enzymic reactions was investigated. Ring-opening polymerization of 1,6-anhydro-3-O-benzoyl-2,4-di-O-benzyl-β-D-glucopyranose (1) with PF₅ as catalyst at low temperature gave a highly stereoregular polymer, which was converted to 2,4-diO-benzyl-(1→6)-α-D-glucopyranan by debenzoylation with sodium methoxide. The polymer was glucosylated according to the glycosyl imidate method. Deprotection of the branched polysaccharide was carried out with sodium in liquid ammonia at -78 °C to give a (1→6)-α-D-glucopyranan having α-D-glucopyranosyl and β-D-glucopyranosyl branches. Only the β-D-glucopyranosyl branch of the polymer was completely removed by enzymatic hydrolysis by the use of cellulase to provide stereoregular (1→6)-α-D-glucopyranan having an α-D-glucopyranosyl branch at the C-3 position. Polymers were characterized by optical rotation, NMR spectroscopy, GPC, and X-ray diffractometry.     

A Convenient Synthesis of Sulfones Using Zinc Mediated Coupling Reaction of Sulfonyl Chlorides with Alkyl Halides in Aqueous Media

An efficient procedure for the preparation of sulfones has been developed through a simple reaction of aromatic sulfonyl chlorides with suitable alkyl halides mediated by commercial zinc powder in aqueous media at 0 °C ～ room temperature.     

Novel Reductive Cleavage Reaction of Thiobenzoates with Samarium Diiodide: Convenient Synthesis of Disulfides

The reductive cleavage of thiobenzoates promoted by samarium diiodide afforded various kinds of disulfides in good yields under mild and neutral conditions.     

A Novel Synthesis of Bis-（1,2,4-triazolyl）-3-disulfides

Manganese triacetate was introduced as a new reagent for radical cyclization of substituted aminothioureas. Bis-（1,2,4-triazolyl）-3-disulfides were generated in 10 min under microwave irradiation.