2,3,8,9-Dibenzo-5,6-(substituted)benzo-1,4-dithio-7-azacyclonona-2,5,8-trienes. Synthesis and mechanistic study

5-(2-Acetamidoaryl)thianthreniumyl perchlorates reacted with potassium hydroxide in methanol at reflux giving 2,3,8,9-dibenzo-5,6-(substituted)benzo-1,4-dithio-7-azacyclonona-2,5,8-trienes 4 in 43 to 75% yields, whereas the reactions of the same compounds with sodium hydride in the absence or in the presence of dimethyl sulfate in refluxing tetrahydrofuran gave N-acetylated and N-methylated 4 in 68 to 96% and 27 to 56% yields, respectively. The mechanism of the formation of the products might be explained by a nucleophilic attack of amide ions 10, 12, and 14 at the ipso-position of the thianthrene ring. A sulfuranyl radical mechanism might be involved in these reactions.     

Selective acetylation of substituted (E)-4(1H)-hydroxyimino-2,3-dihydro-1,8-naphthyridine

We report a selective acetylation of compounds 2 in 1-, 4- or 1,4-position. The treatment of 2 with acetic anhydride gave the compounds 3 and with acetyl chloride the compounds 4 . The 1-acetyl derivatives were obtained starting from 5 via the oxime derivatives 6, 7 and 8 . Tests on phytoiatric antimycotic activity and on reactivation of phosphylated acetylcholinesterase and inhibition of acetylcholinesterase were performed.     

Synthesis of (6,7-dichlorononafluoro-5,6,7,8-tetrahydronaphthalen-2-yl)acetic acid and its transformation into perfluorinated 2-methylnaphthalene and 6-methyl-1,4-dihydronaphthalene

2,3-Dichlorodecafluorotetralin reacted with ethyl cyanoacetate to give ethyl 2-cyano-2-(6,7-dichlorononafluoro-5,6,7,8-tetrahydronaphthalen-2-yl)acetate which was hydrolyzed to (6,7-dichlorononafluoro-5,6,7,8-tetrahydronaphthalen-2-yl)acetic acid. The latter was treated with PCl₅ on heating to obtain 2,2-dichloro-(6,7-dichlorononafluoro-5,6,7,8-tetrahydronaphthalen-2-yl)acetyl chloride which was converted to 2,3-dichlorononafluoro-6-trifluoromethyl-1,2,3,4-tetrahydronaphthalene by the action of SbF₅. The reduction of 2,3-dichlorononafluoro-6-trifluoromethyl-1,2,3,4-tetrahydronaphthalene with zinc in 1,4-dioxane gave perfluoro-6-methyl-1,4-dihydronaphthalene, and in DMF, perfluoro-2-methylnaphthalene.     

Design, synthesis and evaluation of diazadibenzocrown ethers as Pb(2+) extractants and carriers in plasticized cellulose triacetate membranes

The ligands 4,7-diaza-2,3,8,9-dibenzo-15-crown-5 (L1), 4,10-diaza-2,3,11,12-dibenzo-18-crown-6 (L2), 4,10-diaza-2,3,11,12-di(4′-tert-butylbenzo)-18-crown-6 (L3) and N,N-di(methylenecarboxyethoxy) 4,10-diaza-2,3,11,12-dibenzo-18-crown-6 (L4) have been prepared. Partition coefficients and acid dissociation constants for these four diazadibenzocrown ether compounds were determined in water-chloroform. Their effectiveness was assessed in solvent extraction of Pb²⁺ from aqueous solutions into toluene. Ligands L3 and L4 provide high selectivity for Pb²⁺ over Cd²⁺ and Zn²⁺ in transport across plasticized cellulose triacetate membranes.     

Sterically Controlled Regiospecific Cyclization of Aldose-5-ethyl-1,2,4-triazino[5,6- b ]indol-3-ylhydrazones to Linearly Annelated 3-Polyhydroxyalkyl-10-ethyl-1,2,4-triazolo-[4′,3′:2,3]-1,2,4-triazino[5,6- b ]indoles

 Condensation of aldoses with 5-ethyl-3-hydrazino-1,2,4-triazino[5,6-b ]indole gave the corresponding aldose-5-ethyl-1,2,4-triazino[5,6-b ]indol-3-ylhydrazones which were acetylated to their poly-O-acetyl derivatives. The latter underwent sterically controlled regiospecific oxidative cyclization with bromine in acetic acid and sodium acetate to sterically favourable linearly annelated 3-polyacetoxyalkyl-10-ethyl-1,2,4-triazole[4′,3′:2,3]-1,2,4-triazino[5,6-b ]indoles rather than to their sterically unfavourable angularly annelated regioisomers. The regiospecific outcome of this heterocyclization is discussed in terms of electronic as well as steric factors, and the assigned structures have been corroborated on the basis of chemical as well as spectroscopic evidence. De-O-acetylation of the acetoxyindoles with ammonium hydroxide in methanol gave the title compounds. Representative members of the prepared compounds were tested for antimicrobial activity.     

Acetylation of DMSO:PF solutions of cellulose

Three different techniques for esterifying solutions of cellulose dissolved in mixtures of dimethyl sulfoxide (DMSO) and paraformaldehyde (PF) were evaluated and are herein described. The evaluation and development of suitable synthetic procedures and the characteristics of the resulting acetylated cellulose are reported. Glacial acetic acid (glacial HOAc), acetyl chloride (AcCl), and acetic anhydride (Ac₂O) were compared as acetylating agents for solutions of cellulose in DMSO:PF, and it was demonstrated that mixtures of pyridine (Py) and Ac₂O rapidly acetylated the cellulose to yield beige to amber acetone-soluble cellulose acetates which were partially oxidized. These thermoplastic resins exhibited softening points between 80 and 110°C and thermal stabilities (in nitrogen atmospheres) similar to those of native celluloses (350 to 375°C). Degree of acetyl substitution (DS) values ranged from 0 to 2.0 as a function of acetylation time.     

Conformational analysis of sulfur-containing 6-deoxy-l-hexose derivatives by molecular modeling and NMR spectroscopy. A theoretical study and experimental evidence of intramolecular nonbonded interactions between sulfur and oxygen

6-Deoxy-l-mannose diphenyldithioacetal (1) unexpectedly gave the rearranged products phenyl 3,4-di-O-acetyl-2-S-phenyl-1,2-dithio-6-deoxy-beta-l-glucopyranoside (9) and 3,4-di-O-acetyl-2,5-anhydro-6-deoxy-l-glucose diphenyldithioacetal (10) upon treatment with acetyl chloride, while 6-deoxy-l-mannose ethylenedithioacetal (3) yielded (4aR,6S,7S,8R,8aS)-7,8-diacetyloxy-6-methylhexahydro-4aH-[1,4]dithiino[2,3b]pyran (11), whose structure was further confirmed by X-ray diffraction, and 3,4-di-O-acetyl-2,5-anhydro-l-rhamnose ethylenedithioacetal (12). The geometry of the four rearranged products as well as that of 1-thio-6-deoxy-l-mannopyranosides 5 and 7 and their acetyl derivatives 6 and 8 was studied by density functional theory (B3LYP/6-31G) molecular models, in combination with a Karplus-type analysis of the NMR vicinal coupling constants, revealing that the six-membered ring of pyranosides 5-9 and 11 exists in a slightly distorted chair conformation (6-13% distortion) and that the conformational behavior of the 2,5-anhydro-6-deoxy-l-glucose dithioacetals 10 and 12 is strongly influenced by the presence of stabilizing intramolecular nonbonded sulfur-oxygen 1,4- and 1,5-interactions. Compounds 9-12 were formed by a molecular rearrangement via sulfonium ion intermediates followed by stereoselective intramolecular cyclizations as formulated by the quantum chemical calculations performed in the present study.     

Sterically Controlled Regiospecific Cyclization of Aldose-5-ethyl-1,2,4-triazino[5,6-b]indol-3-ylhydrazones to Linearly Annelated 3-Polyhydroxyalkyl-10-ethyl-1,2,4-triazolo-[4′,3′:2,3]-1,2,4-triazino[5,6-b]indoles

Summary.  Condensation of aldoses with 5-ethyl-3-hydrazino-1,2,4-triazino[5,6-b ]indole gave the corresponding aldose-5-ethyl-1,2,4-triazino[5,6-b ]indol-3-ylhydrazones which were acetylated to their poly-O-acetyl derivatives. The latter underwent sterically controlled regiospecific oxidative cyclization with bromine in acetic acid and sodium acetate to sterically favourable linearly annelated 3-polyacetoxyalkyl-10-ethyl-1,2,4-triazole[4′,3′:2,3]-1,2,4-triazino[5,6-b ]indoles rather than to their sterically unfavourable angularly annelated regioisomers. The regiospecific outcome of this heterocyclization is discussed in terms of electronic as well as steric factors, and the assigned structures have been corroborated on the basis of chemical as well as spectroscopic evidence. De-O-acetylation of the acetoxyindoles with ammonium hydroxide in methanol gave the title compounds. Representative members of the prepared compounds were tested for antimicrobial activity. Received November 3, 1999. Accepted December 13, 1999     

Performance testing of a green plasticizer based on lactic acid for PVC

In order to develop alternative green plasticizers, a bio-based plasticizer, acetylated lactic acid 1,4-cyclohexanedimethyl ester(ALCH), with novel molecule geometry was synthesized from l-lactic acid and characterized by FTIR, ¹H NMR and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). The prepared ALCH was mixed with poly(vinyl chloride) (PVC) as plasticizer and the results indicated that the PVC films plasticized by ALCH have better migration and volatility stability than acetyl tributyl citrate (ATBC). In addition, ALCH could endow PVC products with excellent performance of strength, elongation and elasticity. With the substitution of ALCH for ATBC, glass transition temperature (Tg) of PVC films decreased gradually from 61.3°C to 55.0 °C. The self-polymerization of lactic acid gives ALCH better plasticizing effectiveness than ATBC.     

Synthesis of 7-Bromo/5,6-Dimethyl-4 H -1,4-Benzothiazines and Their Conversion into Sulfones

The synthesis of 7-bromo/5,6-dimethyl-4 H -1,4-benzothiazines and their conversion into sulfones is reported. The 7-bromo/5,6-dimethyl-4 H -1,4-benzothiazines were synthesized by the condensation and oxidative cyclization of 2-amino-5-bromo/3,4-dimethylbenzenethiol with g -diketones in dimethyl sulfoxide. The reaction is believed to proceed via an enaminoketone system. 4 H -1,4-Benzothiazine sulfones have been synthesized by the oxidation of 4 H -1,4-benzothiazines using 30% H 2 O 2 in glacial acetic acid. The structures of all newly synthesized compounds have been confirmed by elemental analysis and spectral studies.     

Aromatic amino-claisen rearrangement in the synthesis of ellipticine

A convenient route is described for the preparation of 1,4-dimethylcarbazole — the key compound in the synthesis of the antitumoral alkaloid ellipticine. The interaction of 2,5-xylidine with 3-chlorocyclohexene led to N-(cyclohex-2-enyl)-2,5-xylidine (I), the two-hour heating of which at 140–150°C gave the product of an amino-Claisen rearrangement, 6-(cyclohex-2-enyl)-2,5-xylidine (II) with a yield of 82%. The intramolecular cyclization of compound (II) in polyphosphoric acid (130–140°C, 5 h) led to 5,6,7,8,12,13-hexahydro-1,4-dimethylcarbazole (III) in a yield of 75%. The dehydrogenation of substance (III) by boiling in trimethylbenzene in the presence of Pd/C gave 1,4-dimethylcarbazole (IV) with a yield of 87%. The conditions for performing the reactions and the physicochemical constants of the compounds obtained are given.     

Synthesis of dibenzo derivatives of (4-oxotetrahydropyrano)oxa-14-crown-4 and 1,4,7-trioxacyclohexadeca-8,10,13,15-tetraen-12-one. Transformation of the latter into (4-oxopiperidino)aza-14-crown-4

The reaction of diethyl ketone with 2-{2-[2-(2-formylphenoxy)ethoxy]ethoxy}benzaldehyde in acid medium at room temperature gave 43% of dibenzo(4-oxotetrahydropyrano)oxa-14-crown-4. The condensation of the same compounds in boiling ethanol in the presence of alkali involved cascade transformations leading to the formation of thermody namically more stable dibenzocrownophane which was assigned the structure of 8,9:15,16-dibenzo-1,4,7-trioxacyclohexadec-8,10,13,15-tetraen-12-one (yield 29%). Treatment of an alcoholic solution of the latter with gaseous ammonia or methylamine at 20°C afforded 73–74% of dibenzoaza-14-crowns-4 containing a 4-oxopiperidine fragment.     

Reactions of 6-Amino-5-Cyano-3-Methyl-1,4-Diphenyl-1H 4H-Pyrano[2,3-C]Pyrazole and its Methanimidate

Reaction of 6-amino-5-cyano-3-methyl-1,4-diphenyl- 1H,4H-pyrano[2,3-c]pyrazole 1 with triethyl orthoformate in acetic anhydride gave its methanimidate 2, which reacts with primary aliphatic and aromatic amines to give 4,6-dihydro-3-methyl-1,4-diphenyl-6- (alkyl)pyrazolo[4′,3′:5,6]pyrano[2,3-d]pyrimidine-5(lH)- imine 3 and the starting compound 1 , respectively. Treatment of 1 with o-aminophenol gave 5-(2-benzoxalyl)- 1,4-dihydro-3-methyl-1,4-diphenylpyrano[2,3-c]pyrazol- 6-amine 9.     

Chemistry of thienopyridines. VIII. Substitution products derived from thieno[2,3-b] pyridine 7-oxide

Thieno[2,3-b]pyridine (I) was concerted to the N-oxide (II, 53%) by means of hydrogen peroxide and acetic acid. Nitration of II in sulfuric acid gave 4-nitrothieno[2,3-b]pyridine 7-oxide (III, 50%), while nitration in acetic acid formed the isomeric 5-nitrothieno[2,3-b]pyridine 7-oxide (IV, 54%). Compounds III and IV were reduced to the corresponding 4- and 5-aminothieno[2,3-b]pyridines, respectively. Treatment of III with acetyl chloride gave 4-chlorothieno-[2,3-b]pyridine 7-oxide (XI, 81%), convertible in two steps to 4-(N-substituted amino)thieno-[2,3-b]pyridines (especially of the 4-dialkylaminoalkylamino type) for screening as potential antimalarial drugs. 4-Aminothieno[2,3-b]pyridine reacted with aromatic aldehydes to give Schiff's bases and other products. Mechanisms for some of the reactions are suggested. NMR spectral data are reported for various 4-substituted thieno[2,3-b]pyridine compounds.     

Functionalized 2‐Hydrazinobenzothiazole with Isatin and Some Carbohydrates under Conventional and Ultrasound Methods and Their Biological Activities

Several chemical reactions were carried out on 3‐(benzothiazol‐2‐yl‐hydrazono)‐1,3‐dihydro‐indol‐2‐one ( 2 ). 3‐(Benzothiazol‐2‐yl‐hydrazono)‐1‐alkyl‐1,3‐dihydro‐indol‐2‐one 3a , 3b , 3c have been achieved. Reaction of compound 2 with ethyl bromoacetate in the presence of K₂CO₃ resulted the uncyclized product 4 . Reaction of compound 2 with benzoyl chloride afforded dibenzoyl derivative 5 . Compound 2 was smoothly acetylated by acetic anhydride in pyridine to give diacetyl derivative 6b . Moreover, when compound 4 reacted with methyl hydrazine, it yielded dihydrazide derivative 7 , whereas the hydrazinolysis of this compound with hydrazine hydrate gave the monohydrazide derivative 8 . {N‐(Benzothiazol‐2‐yl‐N′‐(3‐oxo‐3,4‐dihydro‐2H‐1,2,4‐triaza‐fluoren‐9‐ylidene)hydrazino]‐acetic acid ethyl ester ( 9 ) was prepared by ring closure of compound 8 by the action of glacial acetic acid. In addition, the reaction of 2‐hydrazinobenzothiazole ( 1 ) with d ‐glucose and d ‐arabinose in the presence of acetic acid yielded the hydrazones 10a , 10b , respectively. Acetylation of compound 10b gave compound 11b . On the other hand, compound 13 was obtained by the reaction of compound 1 with gama‐d ‐galactolactone ( 12 ). Acetylation of compound 13 with acetic anhydride in pyridin gave the corresponding N¹‐acetyl‐N²‐(benzothiazolyl)‐2‐yl)‐2,3,4,5,6‐penta‐O‐acetyl‐d ‐galacto‐hydrazide ( 14 ). Better yields and shorter reaction times were achieved using ultrasound irradiation. The structural investigation of the new compounds is based on chemical and spectroscopic evidence. Some selected derivatives were studied for their antimicrobial and antiviral activities.     

Synthesis of some dibenzodiazepinone derivatives as potent and m2-selective antimuscarinic compounds

Two series of 5-[[4-[4-(dialkylamino)butyl]-l-cyclohexyl]acetyl], and 5-[(dialkylamino)acyl]-10,11-dihydro-5H- dibenzo[b,e][1,4]diazepin-11-ones were synthesized as potential m2-selective ligands 1,2. Their affinity and selectivity for the muscarinic cholinergic receptor m-AChR subtypes were determined. Replacing a nitrogen with CH in the piperidine ring of 5-[[4-[4-(dialkylamino)butyl]-l-piperidinyl]acetyl]-10,11-dihydro-5H-dibenzo-[b,e][1,4]diazepin-11-ones 3 significantly altered the affinity and selectivity to the muscarinic receptor subtypes.     

Tellurium tetrachloride: Addition to cyclohexene and preparation from tellurium dioxide and trimethylchlorosilane

Tellurium dioxide, trimethylchorosilane, acetyl chloride, or acetyl bromide in glacial acetic acid generated a homogeneous solution. Addition of cyclohexene produced trans-2-halocyclohexyl tellurium trihalides of excellent purity in 70% yield. With dichloromethane or ethanol-free chloroform the same compounds were obtained from heterogeneous reaction mixtures. trans-2-Methoxycyclohexyl tellurium trichloride was obtained quantitatively from tellurium dioxide, trimethylchlorosilane, and cyclohexene in absolute methanol. In the absence of cyclohexene, tellurium tetrachloride was obtained in 91% yield from tellurium dioxide and trimethylchlorosilane in chloroform, and tellurium tetrabromide in 98% yield from tellurium dioxide and acetyl bromide in glacial acetic acid.     

Chemical transformations of 3‐amino‐2‐quinolones

In order to find new antimalarial drugs, an exploration about the chemical properties of the starting compounds 3‐amino‐6‐chloro‐4‐phenyl‐1H‐quinolin‐2‐one ( 1 ) and 3‐amino‐4‐methyl‐1H‐quinolin‐2‐one ( 2 ) was developed. Acylation with acyl chloride, sulfonyl chloride and acetic anhydride were carried out. Despite a previous report [2], when acetyl chloride or acetic anhydride were assayed on 1 , only the diacetyl derivative 7 was obtained. When this compound was heated at reflux temperature in a mixture of acetic acid and acetic anhydride, it was transformed in the oxazoloquinoline 8 . Further reactions of the acyl derivatives with diazomethane afforded 1‐methylated compounds. Compound 2 gave the imine 16 by condensation with 4‐nitrobenzaldehyde.     

Chemistry of fluorinated quinones I. The Diels-Alder reactions of fluoranil

The Diels-Alder reaction of fluoranil with cyclopentadiene, 1,3-butadiene, and 1-acetoxy-1,3-butadiene gave 1,4, 5, 8-bis(methylene)-4a, 8a, 9a, 10a-tetrafluoro-1, 4, 4a, 5, 8, 8a, 9a, 10a-octahydroanthraquinone (I), 2, 3, 4a, 8a-tetrafluoro-4a, 5, 8, 8a-tetrahydro-1,4-naphthoquinone (III), and 5-acetoxy-2, 3, 4a, 8a-tetrafluoro-4a, 5, 8, 8a-tetrahydro-1,4- naphthoquinone (VI), respectively. Hydrogenation of I gave the expected saturated diketone(II). Hydrogenation of III afforded, with elimination of the two tertiary fluorines, 2,3-difluoro-5, 6, 7, 8-tetrahydro-1, 4- dihydroxynaphthalene (IV). In hydrogenation of VI, acetic acid and two moles of hydrogen fluoride were eliminated to give 2,3-difluoro-1, 4-dihydroxynaphthalene(VII). Both dihydroxy compounds IV and VII yielded on oxidation with ferric chloride the corresponding quinones, 2, 3- difluoro-5, 6, 7, 8-tetrahydro-1, 4-naphthoquinone (V) and 2, 3-difluoro-1, 4-naphthoquinone (VIII), respectively. Equivalent amounts of compounds IV and V gave a red-brown semiquinone IX, and a mixture of VI and VIII gave a dark-violet semiquinone X.     

First Synthesis of Double Headed 1,2,4‐Triazino[5,6‐b]indole Acyclo C‐Nucleosides

Heterocyclization of bis(2‐oxo‐indol‐3‐ylidene)‐galactaric acid hydrazide ( 3 ) with a variety of one‐nitrogen cyclizing agents gave the corresponding 1,4‐bis{1,2,4‐triazino[5,6‐b]indol‐3‐yl}‐galacto‐tetritols 4–8 . Acetylation of the latter double headed acyclo C‐nucleosides with acetic anhydride in the presence of pyridine at ambient temperature resulted in N‐ and O‐acetylation to give the corresponding 1,2,3,4‐tetra‐O‐acetyl‐1,4‐bis{1,2,4‐triazino[5,6‐b]indol‐3‐yl}‐galacto‐tetritols 9–13 which were found to exist in centro‐symmetric zigzag conformations 20 . The assigned structures were corroborated by ¹H, ¹³C NMR as well as mass spectra.