1,3-Dimethoxy-1,3-dimethyl-1,3-diphenyl- and 1,3-dimethoxy-1,3-tetraphenyldisiloxanes: synthesis and structure

Russian Chemical Bulletin - 1,3-Dimethoxy- 1,3-dimethyl- 1,3-diphenyl- and 1,3-dimethoxy- 1,3-tetraphenyldisiloxanes were synthesized. Their structures were confirmed by IR and NMR spectroscopy....     

1,3-Cycloaddition von alkinen an hetero-1,3-diene 1-aminopyrrole aus 1,2-diazabuta-1,3-dienen und 1-diethylaminopropin

1-Aminopyrroles (4) are obtained by reaction of 1,2-diazabuta-1,3-dienes (1) and ynamines (2). This reaction represents one of the very rare examples of 1,3-cycloaddition processes of alkynes and hetero-1,3-dienes.     

Photocyclization of 2-chloro-substituted 1,3-diarylpropan-1,3-diones to flavones

The photochemical behavior of 2-halo-substituted 1,3-diarylpropan-1,3-dione strongly depends on the nature of the halogen atom bonded and the presence of electron-donor groups on the phenyl ring. In the case of 2-chloro-1,3-diphenylpropan-1,3-dione and 1-(3,5-dimethoxyphenyl)-3-phenylpropan-1,3-dione, cyclization to flavones was the sole reaction pathway, whereas in the case of 2-chloro-1,3-di(4-methoxyphenyl)propan-1,3-dione, only products derived from alpha-cleavage were observed. 2-Fluoro derivatives of 1,3-diarylpropan-1,3-diones were photostable; on the other hand, 2-chloro-2-fluoro derivates resulted in 3-fluoroflavones.     

Synthesis of 1,3-dihalo-1,3-dioximino-2-propanones

1,3-Dihalo-1,3-dioximino-2-propanones (Hal=Cl or Br), which had been difficult to prepare or unreported, were obtained by the nitrosation of 1,3-dihalo- and 1,3-dihalo-1-oximino-2-propanones by nitrosylsulfuric acid in concentrated H₂SO⁴.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 506–509, February, 1991.     

1H-1,3-diazepines, 5H-1,3-diazepines, 1,3-diazepinones, and 2,4-diazabicyclo[3.2.0]heptenes

Tetrazolo[1,5-a]pyridines/2-azidopyridines 1 undergo photochemical nitrogen elimination and ring expansion to 1,3-diazacyclohepta-1,2,4,6-tetraenes 3, which react with alcohols to afford 2-alkoxy-1H-1,3-diazepines 4 (5), with secondary amines to 2-dialkylamino-5H-1,3-diazepines 16, sometimes via isolable 2-dialkylamino-1H-1,3-diazepines 15, and with water to 1,3-diazepin-2-ones 19. The latter are also obtained by elimination of isobutene or propene from 2-tert-butoxy- or 2-isopropoxy-1H-1,3-diazepines 4 or 5. 1,3-Diazepin-2-one 22B and 1,3-diazepin-4-one 24 were obtained from hydrolysis of the corresponding 4-chlorodiazepines. Diazepinones 19 undergo photochemical ring closure to diazabicycloheptenones 25 in high yields. The 2-alkoxy-1H-1,3-diazepines 4 and 5 interconvert by rapid proton exchange between positions N1 and N3. The free energies of activation for the proton exchange were measured by the Forsén-Hoffman method as DeltaG([double dagger])298= 16.2 +/- 0.6 kcal mol(-1) as an average for 4a-c in CD2Cl2, acetone-d6, and methanol-d4, and 14.1 +/- 0.6 kcal mol(-1) for in 4c acetone/D2O. The structures of 2-methoxy-5,6-bis(trifluoromethyl)-1H-1,3-diazepine 4k, 1,2-dihydro-4-diethylamino-5H-1,3-diazepin-2-one 22bB, and diazabicycloheptanone were 26 determined by X-ray crystallography. The former represents the first reported X-ray crystal structure of any monocyclic N-unsubstituted 1H-azepine.     

Zur Synthese sulfonierter Derivate von 4-Amino-1,3-dimethylbenzol und 2-Amino-1,3-dimethylbenzol

Syntheses of Sulfonated Derivatives of 4-Amino-1, 3-dimethylbenzene and 2-Amino-1, 3-dimethylbenzene Direct sulfonation of 4-amino-1, 3-dimethylbenzene (1) and sulfonation of 4-nitro-1,3-dimethylbenzene ( 4 ) to 4-nitro-1,3-dimethylbenzene-6-sulfonic acid ( 3 ) followed by reduction yield 4-amino-1,3-dimethylbenzene-6-sulfonic acid ( 2 ). The isomeric 5-sulfonic acid ( 5 ) however is prepared solely by baking the acid sulfate salt of 1 . Reaction of sulfur dioxide with the diazonium chloride derived from 2-amino-4-nitro-1,3-dimethylbenzene ( 7 ) leads to 4-nitro-1,3-dimethylbenzene-2-sulfonyl chloride ( 8 ), which is successively hydrolyzed to 4-nitro-1,3-dimethylbenzene-2-sulfonic acid ( 9 ) and reduced to 4-amino-1, 3-dimethylbenzene-2-sulfonic acid ( 6 ). Treatment of 4-amino-6-bromo-1,3-dimethylbenzene ( 12 ) and 4-amino-6-chloro-1, 3-dimethylbenzene ( 13 ), the former obtained by reduction of 4-chloro-6-nitro-1,3-dimethyl-benzene ( 10 ) and the latter from 4-chloro-6-nitro-1, 3-dimethylbenzene ( 11 ), with oleum yield 4-amino-6-bromo-1,3-dimethylbenzene-2-sulfonic acid ( 14 ) and 4-amino-6-chloro-1,3-dimethylbenzene-2-sulfonic acid ( 15 ) respectively; subsequent carbon-halogen hydrogenolyses of 14 and 15 lead also to 6 (Scheme 1). Baking the acid sulfate salt of 2-amino-1, 3-dimethylbenzene ( 17 ) gives 2-amino-1, 3-dimethylbenzene-5-sulfonic acid ( 16 ), whereas the isomeric 4-sulfonic acid ( 18 ) can be prepared by either of the following three possible pathways: Sulfonation of 2-nitro-1,3-dimethylbenzene ( 20 ) to 2-nitro-1,3-dimethylbenzene-4-sulfonic acid ( 21 ) followed by reduction or sulfonation of 2-acetylamino-1,3-dimethylbenzene ( 19 ) to 2-acetylamino-1,3-dimethylbenzene-4-sulfonic acid ( 22 ) with subsequent hydrolysis or direct sulfonation of 17 . Further sulfonation of 18 yields 2-amino 1,3-dimethylbenzene-4,6-disulfonic acid ( 23 ), the structure of which is independently confirmed by reduction of unequivocally prepared 2-nitro- 1,:3-dimethylbenzene-4,6-disulfonic acid ( 24 )(Scheme 2).     

New 1,3-Thiazoles and 1,3-Thiazines from 1-Thiocarbamoylpyrazoles

Summary. New 1,3-thiazoles and 1,3-thiazines are prepared from 1-thiocarbamoyl-pyrazoles. The structures of the title compounds are established by a single crystal structure analysis. Furthermore, antiprotozoal activities of one compound have been determined.     

Substituted propanes: VI. The vibrational spectra and conformations of 1,3-dichloro-, 1,3-bromochloro-, 1,3-dibromo- and 1,3-diiodo-propane

The infrared and Raman spectra of 1,3-dichloro-, 1,3-bromochloro-, 1,3-dibromo- and 1,3-diiodopropane were recorded as liquids and in the crystalline state at low temperatures. Crystals of 1,3-dibromo- and 1,3-diiodopropane formed under ca. 20 kbar pressure at ambient temperature were studied by infrared technique.No evidence was found for the GG₁ conformer (parallel C-halogen bonds), but the other three staggered conformers (GG, AA, and AG) (four for 1,3-bromo-chloropropane) were observed in the liquid. In all the stable low temperature crystals the GG conformers were present, at high pressure 1,3-dibromopropane crystallized in GG and 1,3-diiodopropane in the AA conformation. The C-halogen stretching vibrations have been interpreted in detail. A complete list of fundamentals have been proposed for the GG conformers in each compound, for 1,3-diiodopropane the additional AA fundamentals have been assigned whereas some AG bands were interpreted for each compound.     

Synthesis of 1,3-dialkyl-5-(hetaryl-1-yl)-1,3-dihydrobenzimidazol-2-ones

Reactions of 5-amino-1,3-dialkyl-1,3-dihydrobenzimidazol-2-ones with 2,5-dimethoxytetrahydrofuran and 2,6-dimethyl-γ-pyranone led to the formation of 1,3-dialkyl-1,3-dihydro-5-(pyrrol-1-andл)benzimidazol-2-ones and 1-(1,3-dialkyl-2-oxo-1,3-dihydrobenzimidazol-5-yl)-2,6-dimethylpyridin-4-ones.     

Optisch aktives 1,3-Diferrocenyl-1,3-diphenyl-allen

The title compound 2 was prepared by thermal dehydration of 1,3-diferrocenyl-1,3-diphenyl-propenol (24) with 70% yield.24 was accessible from 1,3-diferrocenyl-propanedione-1,3 (25) in two steps with 10% overall yield: Treatment of25 with phenyllithium gave 1,3-diferrocenyl-3-phenyl-propenone (8) which after repeated reaction with phenyllithium afforded24.Partial optical resolution of2 was achieved by chromatography on triacetyl cellulose in ethanol, whereby both (+)- and (–)-2 were obtained with different enantiomeric purities as could be deduced from the CD-spectra with -values of +0.18 and –1.64, resp., at 480 nm.Attempts to prepare 1,3-diferrocenyl-allene and 1,3-diferrocenyl-1-phenyl-allene failed. In this context several 1,3-diferrocenyl-propenols,-propenones,-propenes,-propanones,-propanes and-butadienes were obtained.

62. Mitt.:M. Benedikt undK. Schlögl, Mh. Chem.109, 805 (1978).     

Skeletal isomerism within 1,3-disilabicyclo[1.1.0]butane and 2,3-disilabuta-1,3-diene derivatives

A bis-adamantane-spiro-fused 1,3-bis(triisopropylsilyl)-1,3-disilabicyclo[1.1.0]butane equilibrates with the corresponding 2,3-bis(triisopropylsilyl)-1,3-disilabuta-1,3-diene with a ratio of 1:19. The 1,3-disilabuta-1,3-diene was fully characterized by a combination of multinuclear NMR and UV-VIS spectroscopies, elemental analysis, and single-crystal X-ray diffraction analysis.     

New 1,3-Thiazoles and 1,3-Thiazines from 1-Thiocarbamoylpyrazoles

New 1,3-thiazoles and 1,3-thiazines are prepared from 1-thiocarbamoyl-pyrazoles. The structures of the title compounds are established by a single crystal structure analysis. Furthermore, antiprotozoal activities of one compound have been determined.     

1,3-Thiazepines

Addition of 2-aryliminohexahydro-1,3-thiazepines to methyl acrylate occurs with participation of the endocyclic nitrogen atom. Structures of the products have been established by IR and mass spectroscopy and x-ray diffraction. The previously described 2-benzylaminotetrahydro-1,3-thiazepine is in fact 2-benzyliminohexahydro-1,3-thiazepine. For Communication 3 see [1]. Institute of Phytochemistry, Academy of Sciences, Republic of Uzbekistan, Tashkent 700170. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, 554–559, April, 1997.     

Comparative research on promising energetic 1,3-diazinane and 1,3-oxazinane structures

The additional carbon centers in 1,3-diazinane and 1,3-oxazinane enable them to covalently bonded geminal-explosophoric groups, leading to unique energetic properties when compared with their homologous energetic structure like RDX. In this paper, a concise synthesis and comparative studies towards 1,3,5-(trinitro1,3-diazinane-5-yl) methyl nitrate and (3,5-dinitro-1,3-oxazinan-5-yl) methyl nitrate (TNOP), two energetic 1,3-diazinane/1,3-oxazinane based promising explosive molecules, are reported. The new germinal nitro/nitroxy explosophoric moieties in the 1,3-diazinane and 1,3-oxazinane frameworks lead to novel structural and energetic properties, which have been investigated through both experimental and computational methods. Densities of the obtained compounds are 1.83 g·cm^?3 and 1.72 g·cm^?3, respectively, along with the detonation velocities of 8714 m·s^?1 and 8112 m·s^?1. The energetic properties of TNNP are comparable to those of RDX. Meanwhile, the low melting point (105 °C) and excellent insensitivity (IS﹥60 J, FS﹥360 N) of TNOP make it an ideal material for the preparation of melt-cast explosives.     

Theoretical investigation on conformational preferences and structural properties of 2-lithio-1,3-diphosphinane and 2-lithio-1,3-dimethyl-1,3-diphosphinane

A new family of dialphosphacyclohexane is introduced which has three nucleophilic centers. The conformational stabilities and structural properties of 2-lithio-1,3-diphosphinane and 2-lithio-1,3-dimethyl-1,3-diphosphinane were investigated computationally by DFT calculations and NBO analyses at B3LYP/6-31+G(d,p). Relative energy trend in 1,3-diphosphinane and 1,3-dimethyl-1,3-diphosphinane conformations explored from steric and hyperconjugative point of view. The stability trend of 2-lithio derivatives based on calculated relative energies in 1,3-diphosphinane is 1d > 1f > 1b > 1a > 1c > 1e and for 1,3-dimethyl-1,3-diphosphinane derivatives is 2f > 2d > 2b > 2a > 2c > 2e. Calculated NBO atomic charges indicate that high positive charge at lithium and small C–Li Wiberg bond indexes in these derivatives are demonstrators of ionic nature of the C–Li bonds. Stereoelectronic interactions, polarizability of phosphorus, and chelate formation between each of phosphorous and lithium are determining factors in stability trend observed in these derivatives. Ease of lithiation in bis(dimethylphosphino)methane, 1,3-diphosphinane, and 1,3-dimethyl-1,3-diphosphinane derivatives was estimated and compared by isodesmic reaction.     

A 1,3-dihydro-1,3-azaborine debuts

We present the first synthesis and characterization of a 1,3-dihydro-1,3-azaborine, a long-sought BN isostere of benzene. 1,3-Dihydro-1,3-azaborine is a stable structural motif with considerable aromatic character as evidenced by structural analysis and its reaction chemistry. Single crystal X-ray analysis indicates bonding consistent with significant electron delocalization. 1,3-Dihydro-1,3-azaborines also undergo nucleophilic substitutions at boron and electrophilic aromatic substitution reactions. In view of the versatility and impact of aromatic compounds in the biomedical field and in materials science, the present study further expands the available chemical space of arenes via BN/CC isosterism.     

Intermolecular 1,3-dipolar cycloaddition of benzonitrile oxide to 2H-1,3-benzothiazines and hexahydro-4H-1,3-benzothiazine

The thermal [3 + 2] intermolecular cycloaddition of benzonitrile oxide to 2H-1,3-benzothiazines 1a-g and hexahydro-4H-1,3-benzothiazine ( 5 ) gives new types of tricyclic angularly and linearly condensed 1,2,4-oxadiazolo-1,3-benzothiazine-fused nitrogen-bridgehead ring systems 2a-g, 6 .     

Preparation of 1-silyl- and 1,3-disilyl-adamantanes

1-Dimethylsilyl- and 1,3-bis(dimethylsilyl)adamantane have been prepared in low yield by Wurtz reaction of dimethylchlorosilane with 1-chloroadamantane or 1,3-dichloroadamantane, respectively. On the other hand, reaction of phenyldimethylsilyllithium with 1-bromoadamantane or 1,3-dibromoadamantane gives essentially quantitative yields of 1-phenyldimethylsilyladamantane or 1,3-bis(phenyldimethylsilyl)adamantane, respectively.     

Synthesis of 1-nitro-1,3-dienes via nitrotrifluoroacetoxylation of 1,3-dienes

Nitrotrifluoroacetate adducts, obtained from 1,3-dienes by reaction with ammonium nitrate in trifluoroacetic anhydride, readily eliminate to afford 1-nitro-1,3-dienes in high yield.     

Stereocontrolled 1,3-phosphatyloxy and 1,3-halogen migration relay toward highly functionalized 1,3-dienes

A double migratory cascade reaction of α-halogen-substituted propargylic phosphates to produce highly functionalized 1,3-dienes has been developed. This transformation features 1,3-phosphatyloxy group migration followed by 1,3-shifts of bromine and chlorine as well as the unprecedented 1,3-migration of iodine. The reaction is stereodivergent: (Z)-1,3-dienes are formed in the presence of a copper catalyst, whereas gold-catalyzed reactions exhibit inverted stereoselectivity, producing the corresponding E products.