Vibrational spectra and molecular conformations of 1,5-dichloro- and 1,5-dibromopentanes and 1,6-dichloro-and 1,6-dibromohexanes

The Raman and IR spectra of 1,5-dichloro- and 1,5-dibromopentanes and 1,6-dichloro-and 1,6-dibromohexanes have been measured. The normal coordinates have been calculated for these molecules using a consistent set of force constants and the molecular conformations studied by analysing the spectra with reference to the results of the calculations. In the crystalline solid state, 1,5-dichloropentane assumes the trans-trans-trans-gauche form and 1,5-dibromopentane, 1,6-dichloro- and 1,6-dibromohexanes assume the all-trans form. The normal coordinate treatment with the well-established force field was of great help in determining the whole molecular form of the relatively large chain molecules.     

Cycloaddition reactions of 1,5-, 1,6- and 4,6-benzo[h]naphthyridinium N-dichloromethylides with dimethyl acetylenedicarboxylate

Summary Cycloaddition reactions of 1,5-, 1,6-, and 4,6-benzo[h]naphthyridinium N-dichloromethylides with dimethyl acetylenedicarboxylate are reported. Ylides were formedin situ from corresponding benzo[h]naphthyridines and dichlorocarbene.

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Cycloadditionsreaktionen von 1,5-, 1,6- und 4,6-Benzo[h]naphthyridinium-N-dichloromethyliden mit Acetylendicarbonsäuredimethylester

Zusammenfassung Es wurden Cycloadditionsreaktionen von 1,5-, 1,6- und 4,6-Benzo[h]naphthyridinium-N-dichloromethyliden mit Acetylendicarbonsäuredimethylester untersucht. Die Ylide werdenin situ aus den entsprechenden Benzo[h]naphthyridinen und Dichlorcarben erhalten.

     

An Efficient Synthesis of Sulfo Lewis X Analog Containing 1-Deoxynojirimycin 1

Abstract

Sulfo Lewis^x analog containing 1-deoxynojirimycin (13) has been efficiently synthesized. Glycosidation of ethyl 2,3,4-tri-O-benzyl-1-thio-β-D-fucopyranoside (5) with O-2,6-di-O-benzoyl-3,4-isopropylidene-β-D-galactopyranosyl)-(1→4)-2,6-di-O-benzoyl-N-benzyloxycarbonyl-1,5-dideoxy-1,5-imino-D-glucitol (4), prepared from O-β-D-galactopyranosyl-(1→4)-1,5-dideoxy-1,5-imino-D-glucitol (1) via 3 steps, and subsequent acid hydrolysis of the isopropylidene group gave the desired trisaccharide diol derivative (7) in good yield. Compound 7 was easily converted into 3′-O-sulfo Lewis^x analog (13) via 6 steps in high yield.

     

Modifications at the 6-O-position of 1-deoxynojirimycin: facile and efficient synthesis of 6-O-alkylated-N-octyl-1-deoxynojirimycin derivatives

A straightforward synthesis of N-alkylated 1-deoxynojirimycin derivatives modified at the 6-O-position has been described. The key intermediate in the synthesis of target compounds was 2,3,4-tri-O-benzyl-1,5-dideoxy-1,5-imino-D-glucitol, which was prepared from 2,3,4,6-tetra-O-benzyl-1,5-dideoxy-1,5-imino-D-glucitol. Optimal conditions have been established for the synthesis of the key intermediate by varying reaction parameters. Reductive amination and subsequent alkylation of the 6-O-position followed by hydrogenolysis were the main reaction steps, which gave target compounds 6-O-ethyl-N-octyl-1,5-dideoxy-1,5-imino-D-glucitol and 6-O-butyl-N-octyl-1,5-dideoxy-1,5-imino-D-glucitol. This synthetic route is flexible and can be useful for the synthesis of other lipophilic iminosugar derivatives.     

Conformation and vibrational spectra of 1,5-hexadiyne (bipropargyl) and 1,5-hexadiyne-1,6-d2

The infrared spectra of 1,5-hexadiyne (bipropargyl) and 1,5-hexadiyne-1,6-d₂ as vapours, liquids, as solutes in various solvents and as crystalline solids at low temperatures and at high pressures have been recorded. Raman spectra were obtained for the liquids, including semiquantitative polarization measurements, and for the low temperature crystals.The data were interpreted in terms of two conformers, anti and gauche, in the vapour and liquid state and one, the anti, in the crystalline forms. A phase transition for 1,5-hexadiyne was observed at ca. 240 K. Both the high and low temperature crystals had molecules in the anti conformer.Interpretation of the spectra in terms of conformational equilibria was facilitated by a thorough vapour phase band contour analysis. With a few exceptions, all the vibrational fundamentals for both conformers were assigned and found to be in good agreement with results from normal coordinate calculations.     

High-resolution electronic spectra and luminescence properties of some benzonaphthyridines at 77 K. absorption and fluorescence spectra of 1,5-, 1,6- a

Absorption and fluorescence spectra of 1,5-, 1,6- and 4,6-benzo[h]naphthyridines (BN) were examined in Shpolskii matrices and in n-butanol at 77 K. Vibrational analysis of quasilinear spectra of 1,6- and 4,6-BN in n-hexane matrices was performed. Calcula- tions of the electronic structure of the isomers examined were done using a modified INDO CI method. The results of the experiments and calculations prove the π, π^* state to be the lowest excited singlet state of 1,6- and 4,6-BN molecules; in 1,5-BN molecule the S₁ (n, π^*) state is strongly perturbed by the nearby s₂(π π^*) state.     

Synthesis of 2H-1,5-benzodioxepin and 2,5-dihydro-1,6-benzodioxocin derivatives via ring-closing metathesis reaction

The synthesis of various 2H-1,5-benzodioxepin and 2,5-dihydro-1,6-benzodioxocin derivatives is described. The key step involves the construction of seven- and eight-membered rings via ring-closing metathesis reaction.     

A nitro sugar mediated synthesis of 6-amino-1,5,6-trideoxy-1,5-imino-d-glucitol (6-amino-1,6-dideoxynojirimycin)

6-Benzoylamino-3-O-benzyl-1,5,6-trideoxy-N-(1,1-diphenylmethyl)-1,5-imino-d-glucitol 12a and its epimer 6-benzoylamino-3-O-benzyl-1,5,6-trideoxy-N-(1,1-diphenylmethyl)-1,5-imino-l-iditol 12b, the protected forms of 6-amino-1,6-dideoxynojirimycin 4 and its C-5 epimer 5, respectively, were easily prepared from diacetone-d-glucose via 6-O-benzoyl-3-O-benzyl-1,2-O-isopropylidene-5-C-nitromethyl-α-d-glucofuranose 7a or 6-O-benzoyl-3-O-benzyl-1,2-O-isopropylidene-5-C-nitromethyl-β-l-idofuranose 7b. 6-Amino-1,6-dideoxynojirimycin 4 (an important precursor of a wide range of glycosidase inhibitors) was easily prepared from 1,5-imino-d-glucitol 12a.     

Molecular modeling of ring-chain equilibria for the ring-opening cross-metathesis of cis,cis-1,5-dimethyl-cycloocta-1,5-diene with ethylene at T=298.15 K

The molecular modeling of ring-opening cross-metathesis of cis,cis-1,5-dimethyl-cycloocta-1,5-diene (1,5-DM-COD), cis,cis-1,6-dimethyl-cycloocta-1,5-diene (1,6-DM-COD) and cis,cis-cycloocta-1,5-diene (COD) with ethylene (ethenolysis) at T=298.15 K using the B3LYP/6-31G(d,p) level of theory reveals that ring-chain equilibrium constants are dependent on the nature of cyclic diene. The ring-chain equilibria for the ethenolysis of 1,5-DM-COD is completely shifted to the formation of monomeric 2-methyl-hexa-1,5-diene.     

trans-Stereoselective intramolecular crossed pinacol coupling of aromatic 1,4-, 1,5-, and 1,6-diketones by electroreduction

Electroreduction of aromatic 1,4-, 1,5-, and 1,6-diketones in the presence of chlorotrimethylsilane and triethylamine gave four-, five-, and six-membered 1,2-diols with trans-stereoselectivity.     

Naphthyridines. Part 3: First example of the polyfunctionally substituted 1,2,4-triazolo[1,5-g][1,6]naphthyridines ring system

Treatment of 1,2,4-triazoles (1) with diethylmalonate in bromobenzene gave 1,2,4-triazolo-[1,5-a]pyridines 2. Chlorination of 2 using POCl₃/DMF (Vilsmeier reagent) led to the isolation of 7-chloro-6-formyl-1,2,4-triazolo[1,5-a]pyridine derivative 4, which reacted with the stabilized ylid 5 to afford 6-ethoxycarbonylvinyl-1,2,4-triazolo[1,5-a]-pyridines 6. Azidation of 6 yielded the corresponding azido compound 7, (Scheme 2). Reduction of 7 with Na₂S₂O₄ gave the corresponding 7-amino compound 8, which cyclized in boiling DMF to give the novel 1,2,4-triazolo[1,5-g][1,6]naphthyridines 9. On the other hand, reacting 7 with one equivalent of PPh₃ (aza-Wittig reaction) in CH₂Cl₂ gave 7-imino-phosphorane derivative 10, and subsequent cyclization in boiling DMF afforded the new 1,2,4-triazolo[1,5-g][1,6]naphthyridine derivative 11 (Scheme 3). However, treatment of 10 with phenyl isothiocyanate in 1,2-dichlorobenzene at reflux temperature gave the new 1,2,4-triazolo[1,5-g][1,6]naphthyridine derivative 14 (Scheme 4). Refluxing 6 with excess of a primary amines 15a,b in absolute. EtOH yielded the corresponding 7-alkyl-amino-1,2,4-triazolo[1,5-a]pyridines 16a,b. These obtained amines 16a,b underwent intramolecular heterocyclization in boiling DMF to give the novel 9-alkyl-1,2,4-triazolo[1,5-g][1,6]-naphthyridines 17a,b, in excellent yields (Scheme 5).     

Conformational analysis of mesocyclic polythioethers : Crystal and molecular structures of 1,4-dithiacycloheptane, 1,5-dithiacyclononane and 1,6-dithiacyclodecane

The crystal and molecular structures of 1,4-dithiacycloheptane (1,4-DTCH), 1,5-dithiacyclononane (1,5-DTCN), and 1,6-dithiacyclodecane (1,6-DTCD) have been determined by single crystal X-ray studies. These compounds crystallize in the space groups P2₁2₁2₁ (No. 19), P2₁/c (No. 14), and P2₁/n, respectively with a = 5.409(1), b = 10.883(2), c = 11.390(2) Å, Z = 4; a = 9.600(4), b = 12.378(8), c = 7.904(3) Å, /gb = 113.31(3)°, Z = 4; and a = 5.290(1), b = 12.853(3), c = 6.850(2) Å, β = 93.39(2)°, Z = 2, respectively. The nonhydrogen atoms were located using direct methods and the hydrogen atoms were found by Fourier difference maps. Full-matrix least-squares refinement led to conventional R factors of 0.0459, 0.0558 and 0.0314, respectively. The conformations adopted by 1,4-DTCH, 1,5-DTCN and 1,6-DTCD, in the crystalline slate, are twist chair (C₂ symmetry), twist boat chair (C₂ symmetry), and boat chair boat (C_2k symmetry), respectively. The transannular S-S distances are 3.583, 4.108 and 4.864 Å, respectively.     

1,5-Diazabicyclo[3.1.0]hexanes and 1,6-diazabicyclo[4.1.0]heptanes: a new method for the synthesis,quantum-chemical calculations,and X-ray diffraction study

A new method was developed for the synthesis of 6-substituted 1,5-diazabicyclo[3.1.0]hexanes and 7-substituted 1,6-diazabicyclo[4.1.0]heptanes by condensation of N-monohalotrimethylene- and N-monohalotetramethylenediamines with carbonyl compounds in the presence of bases. X-ray diffraction studies and quantum-chemical B3LYP/6-31G* calculations demonstrated that the conformations of the resulting bicyclic systems are stabilized by stereoelectronic interactions. As a result, a boat conformation prevails in 1,5-diazabicyclo[3.1.0]hexanes, whereas the energies of chair, half-chair, and boat conformations of 1,6-diazabicyclo[4.1.0]heptanes are equalized.     

1,6‐C‐H and 1,5‐O‐Si Insertion Reactions of Alkylidenecarbene Derivatives of Monosaccharides*

A new protocol has been developed for the generation of alkylidenecarbene derivatives of monosaccharides based on the reaction of trimethylsilylazide and Bu₂SnO with α‐cyanomesylates derived from uloses. When this method is applied to conveniently functionalized carbohydrate derivatives it provides novel heterocyclic ring systems by the rare 1,6‐C‐H or 1,5‐O‐Si insertion reactions.     

Synthesis of N-Glycyl-2,3,4,6-tetra-O-benzyl-1,5-dideoxy-1,5- imino-D-glucitol

1-Deoxynojirimycin (1,5-dideoxy-1,5-imino-D-glucitol, DNJ) and its derivatives have been found to have a number of biological activities, such as anti-HIV, anticancer, anti-diabetic, etc.[1] N-Hydroxylethyldeoxynojirimycin (Miglitol)has been used as a drug for treating diabetic. N-Butyl-1-deoxynojirimycin (NB-DNJ) has show potent anti-HIV-1 and HIV-2 activity without cytotoxicity.[2] Recently, NB-DNJ has been approved for clinical trials as a potential therapy for some glycosphingolipid (GSL) lysosomal storage diseases, which belong to a group of severe and fatal human diseases[3]Therefore, it is very significant to study N-substituted compounds of DNJ.     

1,5-Anhydro-D-Fructose: Stereoselective Conversions to 1,5-Anhydroalditols and Deoxy/Amino Substituted Analogues

ABSTRACT

1,5-Anhydro-D-fructose (1) has been converted into crystalline oximes. 1,5-Anhydroalditols and 2-amino-2-deoxy-1,5-anhydroalditols have been prepared by stereoselective reduction procedures from 1 and from the oximes, respectively.     

Azines and azoles: CXXVI. First example of a novel heterocyclic system: Pyrimido[1,6-<Emphasis Type="Italic">a</Emphasis>][1,5]benzodiazepines

4-Hydroxy-5-(2-R-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-2H-1,3-thiazine-2,6-diones readily undergo acylation at the N¹ atom of the benzodiazepine system by the action of acetic anhydride. Heating of the acetylated products in boiling dimethylformamide leads to the formation of 75–93% of the corresponding 7-acetyl-6-R-6,7-dihydropyrimido[1,6-a][1,5]benzodiazepine-1,3-diones that are derivatives of hitherto unknown fused heterocyclic system, pyrimido[1,6-a][1,5]benzodiazepine. 4-Hydroxy-5-(2-R-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-2H-1,3-thiazine-2,6-diones are converted into 1-(2-aminophenyl)-6-(2-R-vinyl)uracils on heating in boiling DMF.     

Ozonolyse von Olefinen,III: Säurekatalysierte Ozonolyse von 3-Hexen-1,6-und 2-Penten-1,5-dicarbonylderivaten

Summary The ozonolysis of mono-unsaturated compounds containing the structural element =CH-CH₂-R [R=COOH, COOCH₃, CH(OCH₃)₂] was investigated. Reductive ozonolysis of (E)-3-hexene-1,6-dioic acid gives methyl 3,3-dimethoxypropanoate (2), whereas ozonolysis of dimethyl (E)-3-hexene-1,6-dioate (1a) and (Z)-1,1,6,6-tetramethoxy-3-hexene (1b) in a methanolic solution of HCl leads to a mixture of2, dimethyl malonate (3 a) and 1,1,3,3-tetramethoxypropane (3 b). The homologuos derivatives, dimethyl glutaconate (4 a) and 1,1,5,5-tetramethoxy-2-pentene (4 b), were ozonized to give mixtures of2, 3, dimethyl oxalate (5), methyl 2,2-dimethoxyacetate (6 a), and 1,1,2,2-tetramethoxyethane (6 b). The ratios of the various reaction products were determined by gas chromatography. In each case the formation of the bifunctional derivatives2 and6 a was favoured.

     

Synthesis of some new purine-related compounds: Regioselective one-pot synthesis of new tetrazolo[1,5-a]pyrimidine,pyrazolo[1,5-a]pyrimidine and pyrimido[1,6-a]pyrimidine derivatives

An easy and efficient route for the synthesis of some tetrazolo[1,5-a]-, pyrazolo[1,5-a]- and pyrimido[1,6-a] pyrimidine derivatives was described through the reaction of sodium salts of formyl ketones with 5-aminotetrazole, 5-aminopyrazole derivatives and 6-aminothiouracil, respectively. The antimicrobial screening of some derivatives of the prepared compounds has been achieved, and it exhibited a moderate activity against the tested microorganisms.     

Effect of temperature on the surface tension of diluted aqueous solutions of 1,2-hexanediol, 1,5-hexanediol, 1,6-hexanediol and 2,5-hexanediol

Surface tension of aqueous solutions of 1,2-hexanediol (1,2HD), 1,5-hexanediol (1,5HD), 1,6-hexanediol (1,6HD), and 2,5-hexanediol (2,5HD) was measured as a function of composition using the method of capillary rise at 283.15, 288.15, 293.15, 298.15, 303.15 and 308.15 K with emphasis in the very dilute region.