On the synthesis of siloxanes. XXIV. Nucleophilic substitution reactions of 2-functional 1,3-dioxa-2-4,7-trisilacylcloheptanes and 1,3-dioxa-2,4,8-trisilacyclooctanes

2-Hydrogen-1,3-dioxa-2,4,7-trisilacycloheptanes and 2-hydrogen-1,3-dioxa-2,4,8-trisiacyclooctanes, each as a mixture of three configurational isomers, were synthesized and halogenated with chlorine and bromine in the presence of pyridine. The stereochemical course of the halogenation reactions was studied by gas chromatography. 2-Chloro-2,4,7-trimethyl-4,7-bis(trimethyl-siloxy)-1,3-dioxa-2,4,7-trisiacycloheptanes and 2-chloro-2,4,7-trimethyl-4,7-diphenyl-1,3-dioxa-2,4,7-trisilacycloheptanes reacted with alcohols in the presence of pyridine, triethylamine, or 2,6-dimethylpyridine. Gas chromatography, and¹H NMR and²⁹Si NMR spectroscopy were used to investigate the stereochemistry of these substitution reactions. It has been found that all reactions proceed with retention of configuration and that the differences of the relative reactivities of the configurational isomers were distinctly smaller than those observed for reactions of the configurations isomers of functional cyclotrisiloxanes.     

Bromination of deactivated polycyclic aromatic nitro compounds

Bromination of 2,7-dinitro-9,10-phenanthrenequinone, 2,5-dinitro-9,10-phenanthrenequinone, and 2,4,7-trinitrofluorenone with bromine in concentrated sulfuric acid in the presence of acetic acid gave, respectively, 4-bromo-2,7-dinitro-9,10-phenanthrenequinone, 2-bromo-4,7-dinitro-9,10-phenanthrenequinone, and 5-bromo-2,4,7-trinitrofluorenone. No bromination occurred in the absence of nitric acid. The same brominated polynitro compounds can be obtained under analogous conditions directly from unsubstituted 9,10-phenanthrenequinone and fluorenone.     

Conversion of 4-substituted benzo-2,1,3-thiadiazoles to 5-chloro-4,7-dioxobenzo-2,1,3-thiadiazole by action of hydrogen peroxide and hydrochloric acid

Under the influence of hydrogen peroxide and hydrochloric acid in acetonitrile 4-substituted benzo-2,1,3-thiadiazoles form 5-chloro-4,7-dioxobenzo-2,1,3-thiadiazole. 4-Alkoxy- and 4-[(alkoxycarbonyl)methoxy]benzo-2,1,3-thiadiazoles give, in addition, the corresponding 5,7-dichloro derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 114–117, January, 1988.     

Aminonitropyridines and their N-oxides

2,6-Diamino-3,5-dinitropyridine 1-oxide has been prepared by mixed acid nitration of 2,6-diaminopyridine, followed by oxidation using hydrogen peroxide in acetic acid. 3,5-Dinitro-2,4,6-triaminopyridine has been prepared by oxidative amination of 2-chloro-3,5-dinitropyridine or 2,6-diamino-3,5-dinitropyridine using potassium permanganate in liquid ammonia, or by “vicarious nucleophilic amination” of 2,6-diarnino-3,5-dinitropyridine using hydroxylamine in aqueous potassium hydroxide. 3,5-Dinitro-2,4,6-triaminopyridine 1-oxide has been prepared by oxidation of 3,5-dinitro-2,4,6-triaminopyridine using hydrogen peroxide in acetic acid, and by “vicarious nucleophilic amination” of 2,6-diamino-3,5-dinitropyridine 1-oxide. Nmr spectroscopy and single crystal X-ray diffraction studies have shown that these compounds have the planar structures and intra- and inter-molecular hydrogen bonding necessary to confer on the materials the high density, the thermal and chemical stability, and the explosive insensitivity required for new insensitive energetic materials.     

Acid deuterium exchange in benzazoles

The kinetics of acid deuterium exchange in benzazoles carrying electron-donor substituents in the 5-, 6-, or 7-positions have been studied. Mass spectrometric studies have shown that exchange in 5-methoxy-1, 2-dimethylbenzimidazole takes place exclusively at one position in the benzene ring, in 5-chloro-, 7-chloro-,5-methoxy-2-methylbenzothiazole and 6-methoxy-2-methylbenzoxazole simultaneously in two positions, and in 6-methoxy-2-methylbenzothiazole the hydrogen at all three possible positions is exchangeable. Using quantum chemical reactivity indices (CNDO/2) in dynamic and state approximations, the orientational features of the reaction have been ascertained. The lack of agreement between the reactivities of the most reactive sites to exchange in heteroaromatic bicycles of similar structure and electrophilic localization energies is explained by differences in the energy profile of the reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 679–687, May, 1986.     

3-Amino-2,1-benzoisothiazole. Synthesis of some chloro and trifluoromethyl derivatives

The syntheses of the 7-chloro-, 4,7-dichloro-, 5- and 7-trifluoromethyl, 5-chloro-6-trifluoro-methyl- and 5-chloro-7-trifluoromethyl- derivatives of 3-amino-2,1-benzoisothiazole are described. Preparative details are included for a number of the precursors to the benzoisothiazole derivative which have not previously been described. Visible spectra of some azo dyes prepared from the title compounds with a selected coupler are discussed with reference to the substituent effects.     

Some reactions of 2-chloro-3-(<Emphasis Type="Italic">β</Emphasis>-chloroethyl)-4,6-dihydroxypyridine

The chemical properties of 2-chloro-3-(β-chloroethyl)-4,6-dihydroxypyridine (I) have been studied. It has been shown that this compound, which is relatively stable in acids and in neutral and, particularly, in alkaline media, readily splits off hydrogen chloride under mild conditions and is converted into derivatives of 2, 3-dihydro-5-azabenzofuran. The dehalogenation of I in an acid medium yielded 3-(β-chloroethyl)-4, 6-dihydroxypyridine, which was converted into 4, 6-dichloro-3-(β-chloroethyl)pyridine and into 6-chloro-4-methoxy-3-vinylpyridine.     

SYNTHESIS OF SULFONES OF 4H-1,4-BENZOTHIAZINES AND PHENOTHIAZINES

Conversion of 5/7-chloro-4H-1,4-benzothiazines and 1/3-chlorophenothiazines into sulfones is reported. The 5/7-chloro-4H-1,4-benzothiazines were synthesized by the condensation and oxidative cyclization of 2-amino 3/5-chlorobenzenethiol with β diketones in DMSO. The phenothiazines have been synthesized via Smiles rearrangement by the reaction of 2-amino-3/5-chlorobenzenethiol with halonitrobenzenes. 4H-1,4-Benzothiazine and phenothiazine sulfones have been prepared by the oxidation of benzothiazines and phenothiazines with 30% hydrogen peroxide in glacial acetic acid. The structure of all the synthesized compounds has been confirmed by IR and NMR spectral studies.     

Oxidative free radical reactions between 2-amino-1,4-benzoquinones and carbonyl compounds

The manganese(III) initiated oxidative free radical reactions of 2-amino-1,4-benzoquinone are described. The free radical reaction of 5,6-dimethyl-2-methylamino-1,4-benzoquinone (1) provides a novel method for the synthesis of indole-4,7-dione and indole-2,4,7-trione. High chemoselectivity was observed in different solvents. The regioselectivity of this reaction was also studied with 5-methyl-2-methylamino-1,4-benzoquinone (19). In most cases, indole-4,7-diones 20 and 21 were produced in high regioselectivity.     

Allylation of Grignard Reagents: Its Application for the Synthesis of (4E, 7Z)-4,7-Tridecadienyl Acetate,A Sex Pheromone of Potato Tuberworm Moth

Alkylmagnesium halides have been found to react with (Z)-4-benzyloxy-1-chloro-2-butene in presence of HMPA to produce a rearranged product 3-alkyl-4-benzyloxy-1-butene, while in absence of HMPA a normal product (Z)-1-alkyl-4-benzyloxy-2-butene resulted as the predominant product. Latter product has been utilized for the synthesis of (4E, 7Z)-4,7-tridecadienyl acetate, a sex pheromone of potato tuberworm moth.     

Investigation of heterocycles containing nitrogen or sulfur. 47. Reactions of 1,2-dioxo-3a-alkyl-4,7-dichloroxazolidino [3,2-f]pyrido[2,3-b]-1,4-thiazines with saturated cyclic amines. synthesis and structure of derivatives of 1,2-dihydrothiazolo[5,4-b]pyridine

It has been established spectroscopically that 1-N-oxalamides of 2-acyl-5-chloro-1,2-dihydrothiazolo[5,4-b] pyridine are formed in the reaction of 4,7-dichloroxazolidino[3,2-f]pyrido[2,3-b]-1,4-thiazines with morpholine, piperidine and pyrrolidine. The products are a mixture of amide conformers in solution. The reaction intermediate 2-(1-chloro-2-oxobutylthio)-3-pyrrolidinooxamoyl-6-chloropyridine has been isolated and characterized. A proposed reaction scheme is presented.For Communication 46 see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1125–1132, August, 1993.     

Structural, vibrational and quantum chemical investigations on 5-chloro-2-hydroxybenzamide and 5-chloro-2-hydroxybenzoic acid

The Fourier transform infrared (FTIR) and FT-Raman spectra of 5-chloro-2-hydroxybenzamide (5CBA) and 5-chloro-2-hydroxybenzoic acid (5C2HBA) have been recorded in the range 4000-400 and 4000-100 cm(-1), respectively. The complete vibrational fundamental modes of the compounds were assigned and analysed using the observed FTIR and FT-Raman data. The vibrational frequencies determined experimentally were compared with the theoretical wavenumbers calculated from ab initio HF and DFT-B3LYP gradient methods employing 6-31G** and 6-311++G** basis sets. The effect of halogen, hydroxyl groups and hydrogen bonding on the characteristic frequencies of the -COOH and -CONH2 group frequencies have been investigated. In 5CBA and 5C2HBA intramolecular hydrogen bond between a hydroxyl group and CO group makes a six membered ring, which causes the O?H interaction onto the resonance of the benzene ring. Comparison of the positions of the ν(OH) bands shows the ν(OH) band of 5CBA is located at considerably higher frequency which confirms a weaker hydrogen bond than in 5C2HBA.     

Facile synthesis of some novel pyrido[3',2':4,5]thieno[2,3-b][1,4]thiazine-8-carboxylic acids

Model tetrahydropyrido[3',2':4,5]thieno[2,3-b][1,4]thiazines 9a-c were synthesized via reductive lactamization, using sodium dithionite, of the respective 2-[(carboxyalkyl)thio]-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acids 7a-c. The latter derivatives were made via interaction of 2-chloro-7-cyclopropyl-3-nitro-4,7-dihydrothieno[2,3-b]pyridine-5-carboxylic acid (6) with each of alpha-mercaptoacetic, alpha-mercaptopropionic, and alpha-mercaptosuccinic acids and triethylamine in aqueous acetone at room temperature. The structures of 7a-7c and 9a-9c are supported by microanalytical and spectral (IR, MS, NMR) data. Compounds 9a and 9c showed potent inhibitory activity against the IGROV1 (Ovarian Cancer) cell line.     

Synthesis of 4,7-diamino-3-formylcoumarins and azomethines derived from them

A series of 4,7-diamino-3-formylcoumarins has been synthesized by the reaction of 7-dialkylamino-4-chloro-3-formylcoumarins with primary and secondary amines and by the formylation of 4,7-diaminocoumarins by the Vilsmeier reaction. The corresponding Schiff's bases are formed by reaction with primary amines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 338–348, March, 1993.     

Mn2+ complexes of 1-oxa-4,7-diazacyclononane based ligands with acetic, phosphonic and phosphinic acid pendant arms: stability and relaxation studies

A new class of macrocyclic ligands based on 1-oxa-4,7-diazacyclononane was synthesized and their Mn(2+) complexes were investigated with respect to stability and relaxation properties. Each ligand has two pendant arms involving carboxylic (H(2)L(1)--1-oxa-4,7-diazacyclononane-4,7-diacetic acid), phosphonic (H(4)L(2)--1-oxa-4,7-diazacyclononane-4,7-bis(methylenephosphonic acid)), phosphinic (H(2)L(3)--1-oxa-4,7-diazacyclononane-4,7-bis(methylenephosphinic acid)) or phenylphosphinic (H(2)L(4)--1-oxa-4,7-diazacyclononane-4,7-bis[methylene(phenyl)phosphinic acid]) acid moieties. H(2)L(3) and H(2)L(4) were synthesized for the first time. The crystal structure of the Mn(2+) complex with H(2)L(4) confirmed a coordination number of 6 for Mn(2+). The protonation constants of all ligands and the stability constants of their complexes with Mn(2+) and some biologically or biomedically relevant metal ions were determined by potentiometry. The protonation sequence of H(2)L(3) was followed by (1)H and (31)P NMR titration and the second protonation step was attributed to the second macrocyclic nitrogen atom. The potentiometric data revealed a relatively low thermodynamic stability of the Mn(2+) complexes with all ligands investigated. For H(2)L(3) and H(2)L(4), full Mn(2+) complexation cannot be achieved even with 100% ligand excess. The transmetallation of MnL(1) and MnL(2) with Zn(2+) was too fast to be followed at pH 6. Variable temperature (1)H NMRD and (17)O NMR measurements have been performed on MnL(1) and MnL(2) to provide information on water exchange and rotational dynamics. The (17)O chemical shifts indicate hydration equilibrium between mono- and bishydrated species for MnL(1), while MnL(2) is monohydrated. The water exchange is considerably faster on MnL(1) (k(ex)(298) = 1.2 × 10(9) s(-1)) than on MnL(2) (k(ex)(298) = 1.2 × 10(7) s(-1)). Small endogenous anions (phosphate, carbonate, citrate) do not replace the coordinated water in either of the complexes, but they induce their slow decomposition. All Mn(2+) complexes are stable toward air-oxidation.     

Selective reduction of 1-chloro-2-iodoperfluorocycloalkenes with sodium trimethoxyborohydride

In contrast to other chemical reducing agents, it has been found that sodium trimethoxyborohydride will selectively reduce 1-chloro-2-iodoperfluorocycloalkenes to give good yields of 1-hydro-2-chloroperfluorocycloalkenes. The selective displacement of iodine by hydrogen is discussed in terms of HSAB principles.     

First syntheses of natural products with the 2,7-dihydroxy-2H-1,4-benzoxazin-3(4H)-one skeleton

2,7-Dihydroxy-2H-1,4-benzoxazin-3(4H)-one 11 (DHBOA) and 2,4,7-trihydroxy-2H-1,4-benzoxazin-3(4H)-one 14 (TRIBOA) representing aglucones of naturally occurring acetal glucoside type allelo chemicals found in Gramineae have been for the first time synthesized by two pathways both involving selective reductive cyclizations of appropriate 7-benzyloxy-2-nitrophenol derivatives as precursors. TRIBOA 14 and its bioactive naturally occurring 7-methyl ether DIMBOA have been found to undergo a hitherto unknown transformation to the corresponding 2,6-dibromo substituted lactam forms 20 and 21 in the presence of hydrogen bromide in acetic acid, which is of value in a better understanding of the possible mode of bioactivity.     

Oxidation of halohydroxybenzo-2,1,3-thiadiazoles with nitric acid

4,5-Dioxobenzo-2,1,3-thiadiazole has been synthesized. Its structure was proven by conversion to the known 4,5-dioximinobenzo-2,1,3-thiadiazole and to 2,1,3-thiadiazolo[4,5-a]phenazine, and by reduction to 4,5-dihydroxybenzo-2,1,3-thiadiazole. Oxidation of 5,6-dichloro-4,7-dihydroxy- and 5,7-dichloro-4-hydroxy-benzo-2,1,3-thiadiazoles forms 5,6-dichloro-4,7-dihydroxybenzo-2,1,3-thiadiazole, of known structure, and 7-chloro-4,5-dioxobenzo-2,1,3-thiadiazole; the latter by reaction with ortho-phenylene diamine is converted to 4-chloro-2,1,3-thiadiazolo[4,5-a]phenazine.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 850–852, June, 1987.     

Thermodynamic studies of the binding of bidentate nitrogen donors with methyltrioxorhenium (MTO) in CHCl3 solution

Methyltrioxorhenium (MTO) adduct formation with bidentate nitrogen donors 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (Me(2)bpy), 4,4'-di-tert-butyl-2,2'-bipyridine (tBu2bpy), 1,10-phenanthroline (phen), 5-methyl-1,10-phenanthroline (5-Mephen), 5-chloro-1,10-phenanthroline (5-Clphen), 4,7-dimethyl-1,10-phenanthroline (Me2phen) has been studied at different temperatures in CHCl3 solution. Spectrophotometeric measurements have been carried out to obtain the thermodynamic parameters. All complexes are enthalpy stabilized whereas the entropy changes counteract the adduct formation. The results are discussed in terms of different basicities of the bidentate N-donors.     

Rearrangement of 1-acetylindoxyl oxime to 1-acetyl-2-chloro-3-iminoindoline hydrochloride

Rearrangement of 1-acetylindoxyl oxime upon treatment with hydrogen chloride in acetic acid results in the formation of 1-acetyl-2-chloro-3-iminoindoline hydrochloride. Hydrolysis and acylation of the latter have been studied, along with reaction of 1-acetyl-2-chloro-3-(-chloroacetyl)aminoindole with N- and S-nucleophiles.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 617–621, May, 1990.