Synthesis and characterization of some new 1,2,3-thiadiazole and 1,2,3-selenadiazole triterpene derivatives from allobetulone and 2-oxoallobetulin

Abstract

The synthesis of new 1,2,3-thiadiazole and 1,2,3-selenadiazole derivatives from triterpenoid ketones has been investigated via the corresponding semicarbazones. The intermediates 5, 8 have also been isolated, separated and their structures identified. The Hurd–Mori reaction and Lalezari method have been applied to synthesize a series of new substances 6 and 7. The regioselectivity of the functionalization mostly was centered at the C-3 position for the products 9 and 10. The structures of these compounds were confirmed by 2D-NMR spectroscopy.     

High Performance Liquid Chromatography of New Potential Anxiolytic Drugs and Related Benzodiazepines: A Comparative Study of Hydrophobicity

Abstract

A comparative study of hydrophobicity in diazepam (5) chlordizepoxide (6), buspirone (7) and four related pyrrolothieno-1,4-dizepine systems (1–4) has been carried out, using HPLC (RPC) technique. The capacity factors (K') of compounds studied have been measured in five different elution conditions (mobile phase in which the percentage of methanol varies). The capacity factors (K'₀) corresponding to the absence of organic solvent in the mobile phase have been calculated. Correlations among hydrophobic parameters of series 1, 2, 3, and 4 have been established and K'₀ of compounds not yet synthesized have been calculated.     

SYNTHESE DU FOSTEDIL (4-(2-BENZOTHIAZOLYL) BENZYLPHOSPHONATE DE DIETHYLE) A PARTIR D'IMIDATES N-ACYLES

Fostedil (diethyl 4-(benzothiazol-2-yl) benzylphosphonate) 7 has been synthesized efficiently by treatment of 2-(4-bromomethylphenyl) benzothiazole 6 with triethylphosphite. The latter (6) has been prepared by bromation of benzothiazole 3c. N-acylimidates 1(a–d) react with 2-aminobenzenethiol 2 to lead to the corresponding benzothiazoles 3(a–d) after elimination of primary amide 5. The structure of these products have been unequivocally confirmed by means of IR, ¹H, ¹³C, and ³¹P NMR spectroscopy and mass spectra.     

Titanium-dioxide-mediated photocatalysed reaction of selected organic systems

The photocatalysed reaction of four selected organic systems, namely dichlone (1), 2-amino-5-chloropyridine (2), benzoyl peroxide (3) and 3-chloro perbenzoic acid (4), has been investigated in an acetonitrile/water mixture in the presence of titanium dioxide and oxygen. An attempt has been made to identify the products formed during the photo-oxidation process using the GC/MS analysis technique. The photolysis of dichlone (1) leads to the formation of phthalic anhydride (11) and 1H-indene-1,2,3-trione (10), whereas 2-amino-5-chloropyridine (2) gave rise to 2,2′-diamino bipyridyl (14), 2-pyridinamine (16), 2-hydroxy-5-chloropyridine (18), bipyridyl (19) and 2-amino bipyridyl (21). The photolysis of benzoyl peroxide (3) yielded a mixture of products such as benzoic acid (24), biphenyl (27), biphenyl-4-carboxylic acid (29) and benzoic acid phenyl ester (30). Two intermediate products, as 3-chlorobenzaldehyde (35) and hydroxyl added 3-chlorobenzaldehyde (33), have been identified in the case of 3-chloro perbenzoic acid (4). The products have been identified by comparing the molecular ion and mass fragmentation peaks of the products with those reported in the GC-MS library. A probable mechanism for the formation of the products has been proposed.     

Fluorination of tertiary alcohols derived from di-O-isopropylidenehexofuranose and O-isopropylidenepentofuranose

The stereo- and regioselectivity of the dehydroxyfluorination of various tertiary alcohols derived from di-O-isopropylidenehexofuranose and 1,2-O-isopropylidenepentofuranose has been studied. Reactions have been accomplished using DAST and PFPDEA (1,1,3,3,3-pentafluoropropene-diethylamine adduct) as fluorinating reagents. Dehydroxyfluorination of allylic alcohol 2a has occurred with an inversion of configuration and allylic rearrangement leading to two chiral regioisomers 6a and 7a. Analogous reaction of 2b has given allylic chiral fluoride 7b as the only product. In case of phenylacetylene, styryl and benzylic alcohols 3a/3b-5a/5b the single diastereoisomers 8a/8b-10a/10b have been obtained. Additionally, the participation of 1,2-O-substituent effect in carbocation stabilization during fluorination have been discussed.     

Titanium-dioxide-mediated photocatalysis reaction of three selected pesticide derivatives

The photocatalysis reaction of three selected pesticide derivatives, namely methoxychlor (1), chlorothalonil (2) and disulfoton (3), has been investigated in an acetonitrile/water mixture in the presence of titanium dioxide and oxygen. The change as a function of irradiation time has been monitored using the UV spectroscopic analysis technique. An attempt has been made to identify the product formed during the photooxidation process through GC/MS analysis technique. The photolysis of methoxychlor (1) led to the formation of methoxychlor olefin (4) and 4,4-dimethoxybenzophenone (9), whereas chlorothalonil (2) gave rise to 2,3,4,5-tetrachlorophenol (17) as the only product. On the other hand, the photolysis of disulfoton (3) under analogous conditions gave disulfoton sulfoxide (25) and phosphorodithioic acid (21). All the products have been identified by comparing the molecular ion and mass fragmentation peaks of the products with those reported in the library. A probable mechanism for the formation of the products has been proposed.     

<Emphasis Type="Italic">N</Emphasis>-Alkoxy-3,5-dinitro-4-aminobenzoic acid derivatives with controlled physico-chemical properties

Starting from 4-chloro-3,5-dinitrobenzoic acid 1, compounds 2–10 (N-alkoxy-3,5-dinitro-4-aminobenzoic acid esters where alkoxy stands for methoxy, carboxymethoxy, triphenylmethoxy, or corresponding amides) have been obtained, from which compounds 3–5 and 7–10 are new, and for the known compounds 2 and 6 the synthetic procedure has been improved. The new derivatives have been characterized by appropriate means (IR, UV–Vis, ¹H- and ¹³C-NMR, fluorescence) and their properties were studied. Thus, depending on their structure, the compounds have acid properties, fluorescence and complexing properties with alkaline cations.     

Group 3 and lanthanide triflate-complexes with [N,N,O]-donor ligands: synthesis,characterization, and cytotoxic activity

Group 3 and rare-earth triflate-complexes M(OTf)₂(bdmpza) {M?=?Sc (1^Sc ), Y (1^Y ), La (1^La ), Sm (1^Sm ), Eu (1^Eu ) OTf?=?SO₃CF₃} bearing the heteroscorpionate ligand bdmpza {bdmpza?=?bis(3,5-dimethyl-pyrazol-1-yl)acetate} have been synthesized and characterized, together with the yttrium and europium complexes M(OTf)(bdmpza)₂ {M?=?Y (2^Y ), Eu (2^Eu )}. The photoluminescent behavior of 2^Eu has been investigated. The coordination mode of the [N,N,O]-donor in these complexes has been elucidated by DFT calculations. The cytotoxic effect of selected complexes and of the free ligand toward HeLa cells has been evaluated.     

SYNTHESIS AND THERMAL REARRANGEMENT OF 2-ALKOXYCARBONYL-3-ALKYL-4H-BENZO[b][1,4]THIAZINES

Abstract

The title compounds (4b-d) together with the benzothiazolines (5b-d) have been obtained by a reaction between 2,2′-dithiodianiline (1) and β-keto esters (2b-d). The reaction between 1 and the β-keto ester 2a gives 1,4-benzothiazine 3a in addition to the benzothiazoline 5a.

It has been established that the 1,4-benzothaizines 4b-d undergo an acid-catalysed thermal rearrangement involving a [1,3] shift of the sulfur atom, giving rise to the isomeric 1,4-benzothiazines 3b-d.     

New Structures from Multiple Rearrangements of Propargylic Dialkoxy Disulfides

Abstract

Sundry dipropargyloxy disulfides have been successfully prepared and their rearrangement paths and products have been found to be dependent upon their substitution pattern. Inter alia compounds of two heretofore unknown structure types— 10 and 11 on the one hand and 14 and 15 on the other—have been obtained and characterized.     

Guanylurea derivatives of diorganotin(IV) dichloride

A series of organotin complexes with guanylurea (H₂L) have been synthesized. All the complexes 1–8, BuMeSnClHL, PhEtSnClHL, PhMeSnClHL, PhBuSnClHL, BuMeSnL, PhEtSnL, PhMeSnL, and PhBuSnL have been characterized by elemental analysis, FTIR, and multinuclear spectroscopic techniques. Complexes 1–4 are five-coordinate whereas 5–8 are four-coordinate.     

Synthesis,crystal structure,and antibacterial activity of two new mononuclear nickel(II) complexes of a NNS Schiff base

Two new mononuclear nickel(II) complexes, [Ni(L)(N₃)] (1) and [Ni(L)₂(NCS)₂] (2), where HL = 2-{[phenyl(pyridin-2-yl)methylidene]amino}benzenethiol, a tridentate Schiff base derived from 2-aminothiophenol and 2-benzoylpyridine, have been prepared and characterized. The syntheses of 1 and 2 have been achieved by the reaction of equimolar amounts of nickel perchlorate and HL in the presence of azide and thiocyanate, respectively. The complexes have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction, and other physicochemical studies. Structural studies reveal that 1 and 2 adopt two different geometries, distorted square planar in 1 and octahedral in 2. The two mononuclear complex units are held together by π…π or C–H…π weak intermolecular interactions to develop supramolecular networks in their solid states. The antibacterial activity of 1, 2 and their constituent Schiff base has been tested against some gram(+) and gram(?) bacteria.     

Dioclins A and B,new antioxidant flavonoids from Dioclea reflexa

Dioclins A (1) and B (2), the new flavonoids, have been isolated from the ethyl acetate soluble fraction of the roots of Dioclea reflexa along with 3,5-dihydroxy-4 methoxybenzoic acid (3), lupeol (4) and the rare dipeptide, auratiamide acetate (5). Their structures have been elucidated by spectroscopic techniques. The compounds 1 and 2 showed a significant antioxidant activity in DPPH radical scavenging assay.     

Synthesis,crystal structures,and catalytic activities of palladium imidazole complexes formed by 2-hydroxyethyl group cleavage

N-4,6-dimethyl-2-pyrimidinylimidazole 1 and its hydroxyethyl derivative 1-(2-hydroxyethyl)-3-(4,6-dimethyl-2-pyrimidinyl)imidazolium chloride 2 have been synthesized and characterized. The attempted synthesis of bis(N-heterocyclic carbene)palladium complexes via the direct reaction of 2 with Pd(OAc)₂ results in the unexpected formation of a bis(N-arylimidazole) palladium complex 3. Additionally, the analogous bis(N-methylimidazole) palladium complex 4 has also been synthesized by the above method. Compounds 1–4 were characterized by elemental analysis, IR, and ¹H NMR. Additionally, their crystal structures have been determined by X-ray diffraction. Complexes 3 and 4 were found to be efficient catalysts for the Suzuki reaction.     

Selective Benzoylation of 1-(β-D-Xylopyranosyl)-3,5-dimethylpyrazole

Abstract

Selective benzoylation of l-(β-d-xylopyranosyl)-3,5-dimethylpyrazole (1) has been performed to give 2,3,4-tri- (2), 3,4-di- (3), 2,4-di- (4), 3- (5) and 4-benzoate (6). The O-acetyl derivatives of compounds 3 and 4 (7, 8), di-O-acetyl of 5 and 6 (9, 10) and O-methanesulphonyl of 3 and 4 (11, 12) have been obtained. The relative reactivity of the hydroxyl groups of 1 was HO-4 ≥ HO-3 ? HO-2. The analysis of ¹ H NMR and ¹³C NMR spectra of 1-12 is presented.     

Efficient and versatile catalysis for β-alkylation of secondary alcohols through hydrogen auto transfer process with newly designed ruthenium(II) complexes containing ON donor aldazine ligands

A new series of ruthenium(II) carbonyl complexes, [RuCl(CO)(EPh₃)₂(L_1-2)] (1–4) (E = P or As; H₂L₁ = salicylaldazine, H₂L₂ = 2-hydroxynaphthaldazine), have been assembled from ruthenium(II) precursors [RuHCl(CO)(EPh₃)₃] and bidentate ON donor Schiff base ligands (H₂L_1-2). Both ligands and their new ruthenium(II) complexes have been characterized by elemental analyses, spectroscopic methods (UV, IR, NMR (¹H, ¹³C, ³¹P) as well as ESI mass spectrometry. The molecular structures of H₂L₁ and 1 have been confirmed by single crystal X-ray diffraction. Based on the above studies, an octahedral coordination geometry around the metal center has been proposed for 1–4. To investigate the catalytic effectiveness of 1–4, the complexes have been used as catalysts in β-alkylation of secondary alcohols with primary alcohols and synthesis of quinolines. The effect of solvent, time, base, catalyst loading, and substituent of the ligand moiety on the reaction was studied. Notably, 1 was a more efficient catalyst toward alkylation of a wide range of alcohols and quinolines synthesis. The reusability of the catalyst was checked and the results showed up to six catalytic runs without significant loss of activity.     

Bishomocamphenilon,Bishomocamphen und Bishomocamphenilansäure: Synthesen in der Isocamphanreihe, 32. Mitt.

Summary Syntheses of the title compounds are described and their olfactive properties discussed. Bishomocamphenilone (2) has been prepared by a Diels-Alder reaction of acrylonitril and cycloheptadiene-1,3 via the bicyclonitril5 which upon geminal chlorination and alkaline oxidation furnished the bishomonorbornanone9 which then could be transformed into2 by twofold methylation.14 has been prepared by action ofMeLi upon2 and bishomocamphene by dehydration of14. Hydroboration of this olefine3 yielded the alcohol15, which could be oxidized to the corresponding aldehyde13 and bishomocamphenilanic acid (4). The configurations of all new compounds has been ascertained.

Siehe Lit. [3]     

Polyoxometalate tri-supported transition metal complexes containing mixed-valent transition metal ions

Three compounds, [AsMo₈V₆O₄₂][Cu(2,2?-bpy)₂]₂[Cu(2,2?-bpy)]·4H₂O (1), [PMo₈V₆O₄₂][Cu(2,2?-bpy)₂]₂[Cu(2,2?-bpy)]·3H₂O (2) and [PMo₈V₆O₄₂][Cu(2,2?-bpy)₂]₂[Cu(2,2?-bpy)]·3.5H₂O (3), have been synthesized under hydrothermal conditions and characterized by IR, UV–vis, XRD, TG, elemental analysis, and X-ray diffraction analysis. Single-crystal X-ray structure analysis reveals that 1 and 2 are isostructural and isomorphous, whereas 2 and 3 are polymorphs. Polymorphs of 1 have not been synthesized yet. The mixed-valent transition metal ion in 1–3 has been further confirmed by TG analyses. Catalytic properties of 1 and 2 have also been studied.     

Synthetic studies on the molybdenum cofactor: Total synthesis of pterindithiolenes by direct dithiolene formation from suitable pterin alkynes

A novel, efficient total synthesis of a series of pterindithiolenes (15, 16, 17 and 18) [(5,6-dihydro-[1,4]dithiin or 6,7-dihydro-5H-[1,4]dithiepin systems respectively for six and seven membered dithiolenes] has been reported. The six membered quinoxaline thioketal 9 and seven membered quinoxaline dithiolene 11 have also been synthesized from quinoxaline acetylenic alcohol 5 and the corresponding acetylenic ketone 10 respectively. The synthesis of five membered pterin thioketals 12 and 13 along with the conversion of 13 to the dithiolene 14 by the reaction with NBS is also reported.     

Syntheses,crystal structures,and antibacterial activities of manganese(III), nickel(II), and copper(II) complexes containing a tetradentate Schiff base

Three new mononuclear Schiff-base complexes, namely [Mn(L)Cl] (1), [Ni(L)] (2), and [Cu(L)] (3), where L?=?anion of [N,N′-bis(2-hydroxybenzophenylidene)]propane-1,2-diamine, have been synthesized by reacting equimolar amounts of the respective metal chloride and the tetradentate Schiff base, H₂L, in methanol. The complexes have been characterized by microanalytical, spectroscopic, single-crystal X-ray diffraction, and other physicochemical studies. Structural studies reveal that 1 adopts a distorted square-pyramidal geometry whereas 2 and 3 are isotypic with distorted square-planar geometries. The antibacterial activities of 1–3 along with their Schiff base have been tested against some Gram(+) and Gram(?) bacteria.