Synthesis of 16-substituted 23,24-dinorcholane derivatives

16-Substituted 22,24-dinorcholanes with variously modified A and B rings were synthesized starting from 17-oxo steroids through 17-ethylidene derivatives via ene reaction and subsequent transformations at the Δ¹⁶-bond.     

Microwave-assisted synthesis of non-substituted tripyrrane, tetrapyrrane and pentapyrrane

The microwave-assisted one-step condensation of aqueous formaldehyde with pyrrole was successfully applied for the preparation of non-substituted tri-, tetra- and pentapyrranes with reasonable yields. All three compounds are important precursors to advanced porphyrins and porphyrin analogs. The advantages of this method are short reaction times, clean reaction mixtures and work in the non-toxic and environment friendly solvent—water.     

Synthesis of new derivatives of 1,5,9,13-tetraaza[16]annulene using 2-substituted vinamidinium salts

New 7,15-dibromo-, 7,15-di(bromomethyl)-, and 7,15-di[4-(bromomethyl)phenyl]-1,5,9,13-tetraaza[16]annulene derivatives are synthesized via the condensation reaction of 2-substituted vinamidinium salts [2-substituted 3-(dimethylamino)-N,N-dimethyl-2-propen-1-aminium salts] with 1,8-diaminonaphthalene in acetonitrile/acetic acid. The ultraviolet spectral behavior of these compounds is examined in DMSO.     

Synthesis of 7-substituted tetracycline derivatives

[formula: see text] The synthesis of 7-substituted tetracycline derivatives has been accomplished in high yield from 7-halotetracyclines by modified Suzuki and Stille coupling protocols. These novel derivatives may serve as a new class of tetracycline antibiotics effective against multi-antibiotic-resistant bacteria.     

Synthesis of 2-substituted bamipine derivatives

2-Substituted derivatives of bamipine and its 1-phenyl analogue have been prepared in several steps from dihydropyridine-2(1H)-thiones. The configurations and the conformations of the formed diastereoisomers have been investigated by NMR spectroscopy. The antimycobacterial activities of the title compounds have been examined.     

Hexafluorosilicates of 2-substituted anilinium derivatives

The reaction of 45% fluorosilicic acid with methanol solutions of several 2-substituted anilines(L) gave hexafluorosilicates (LH)₂SiF₆. The products were studied by elemental analysis, IR spectroscopy, mass spectrometry, and thermogravimetry. The solubility and the hydrolytic stability of the salts were estimated. The structure of the complex [CH₃O(O)CC₆H₄NH₃]₂SiF₆ was determined by single-crystal X-ray diffraction. The ionic structure is composed of centrosymmetric SiF ₆ ^2? anions (the average Si-F bond length is 1.679(1) Å) and the [CH₃O(O)CC₆H₄NH₃]⁺ cations. The NH ₃ ⁺ group is the donor for the inner-cation H-bond with the carbonyl oxygen atom (NH···O), and for two ion-ion H-bonds (NH···F). The Si-F bond lengths correlate with the strengths of the H-bonds involving the corresponding fluorine atoms.     

Synthesis of 1-substituted dihydropyrimidinone and quinazolinone derivatives

Condensation of N-substituted -alanines (synthesized from anthranilic acid or its esters and acrylic acid) with urea afforded the corresponding 1-substituted dihydropyrimidinedione and quinazolinedione. When potassium thiocyanate was employed in the reaction instead of urea, decarboxylation and desulfuration occurred.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1391–1394, October, 1992.     

A convenient, high-yield synthesis of 1-substituted uracil and thymine derivatives

Novel reagents for the synthesis of 1-substituted uracil and thymine derivatives have been developed. The aminolysis of 2- or 4-nitrophenyl 3-ethoxyacryloylcarbamate and 3-ethoxy-2-methylacryloylcarbamate with a variety of primary amino derivatives proceeded smoothly under very mild reaction conditions yielding almost quantitatively the 1,3-disubstituted urea derivatives. Their subsequent cyclization provided the 1-substituted uracil and thymine compounds, in almost quantitative yield.     

Novel 2,7-substituted pyrene derivatives: syntheses, solid-state structures, and properties

A novel series of pyrene derivatives 3-6 functionalized with different aromatic substituents at 2,7-positions of the pyrene core have been readily synthesized by Suzuki coupling reactions. Single crystals suitable for X-ray crystallographic analysis of compounds 3-6 were all successfully obtained. The optical, electrochemical, and thermal properties of these newly synthesized compounds were thoroughly investigated and discussed. Theoretical calculation was adopted to study the geometric and electronic structure of compounds 3-6. Additionally, preliminary studies demonstrated that field-effect transistors using compound 3, 5, and 6 performed as p-type semiconductors, in which a field-effect mobility as high as 0.018 cm² V⁻¹ s⁻¹ and current on/off ratio of 10⁶ were achieved from compound 6.     

POCl3-mediated synthesis of 2-substituted benzimidazolyl-coumarin,benzimidazolyl-indole,and styrylbenzimidazole derivatives

2-Substituted benzimidazolyl heterocycles and styrylbenzimidazoles have been synthesized by the reaction of substituted o-phenylenediamine with different heterocyclic carboxylic acids and cinnamic acid respectively in the presence of POCl₃ as a solvent and catalyst. The proposed reaction has advantageous features of good yields, short reaction times, and operational simplicity. In addition, the scope and limitations were explored, and a plausible reaction mechanism was proposed. The synthesized molecules were characterized by infrared, ¹H NMR, ¹³C NMR, and mass spectral data. Further, single crystals of 2-(1H-indol-2-yl)-1H-benzo[d]imidazole have been developed and structural parameters were collected from x-ray diffraction data.     

Synthesis of 1-triphenylgermylpropiono-4-substituted semicarbazides,thiosemicarbazides and their heterocyclic derivatives

Twenty-one new organogermanium compounds with the formulae Ph₃GeCHR¹CH₂CONHNHC(X)NHR² (1) (R¹=H, Ph; = Ph, p-CH₃Ph, O -CH₃Ph, p-ClPh, COPh, X = S, O) and (R¹ = H, Ph; R² = Ph, p-CH₃Ph, o-CH₃Ph, p-ClPh; X=S, O) were synthesized and characterized by elemental analysis, ¹H NMR, IR, MS and X-ray diffraction techniques. Compounds l were prepared by the reactions of Ph₃GeCHR¹CH₂CONHNH₂ with R²NCX in chloroform in 77-94% yields, and 2 were obtained by refluxing l with sodium hydroxide (8%) with yields of 55-94%.     

Synthesis and characterization of 5-substituted 1,3-diazacyclohexane derivatives

Three synthetic routes to 5-substituted 1,3-diazacyclohexane derivatives 1 are reported. The first method involves treatment of 1, 3-diaminopropan-2-ol 2 with paraformaldehyde to yield 5-hydroxy-1, 3-diazacyclohexane 3. A second method is based on the condensation of 2-bromo-2-nitro-1,3-propanediol with tert-butylamine and formaldehyde to yield 1,3-di-tert-butyl-5-bromo-5-nitro-1, 3-diazacyclohexane 22. The third method relies on the cycloalkylation of methylenebisacetamide with 3-chloro-2-chloromethyl-2-propene to provide 5-exomethylene-1, 3-diacetyl-1,3-diazacyclohexane 28. Functional group manipulations of 3, 22, and 28 provide a number of novel 1,3-diazacyclohexanes functionalized at the 5-position.     

Synthesis and antioxidant activity of 3-substituted guaiazulene derivatives

A series of 3-substituted guaiazulene derivatives has been synthesized and their antioxidant properties were evaluated by monitoring their capacity for scavenging the stable free-radical DPPH. 3-Vinylguaiazulene was the most potent, possessing antioxidant activity superior than alpha-tocopherol. These derivatives were also moderate inhibitors of the proliferation of human promyelocytic leukemia cells.     

Design,synthesis, and antimicrobial activity of novel 5-substituted indole-2-carboxamide derivatives

Research on Chemical Intermediates - A series of novel, bioactive 5-substituted indole-2-carboxamide derivatives (10a–t and 14a–k) are synthesized by the coupling of 5-substituted...