Synthesis of 2, 2, 5, 5-tetramethyltetrahydrothiophene

Under the conditions of the Grignard reaction, 2, 5-dimethyl-2, 5-hexanediol has been obtained from diethyl succinate. Under the action of sulfuric acid, the latter has been cyclized to 2, 2, 5, 5-tetramethyl-tetrahydrofuran which, in its turn, by treatment with phosphorus pentasulfide, has given 2, 2, 5, 5-tetramethyltetrahydrothiophene. Its reaction with methyl iodide has given 2, 2, 5, 5-tetramethyltetrahydrothiophene methiodide.     

Oxetane from A-nor-steroides: 2-alpha, 5-oxido-A-nor-5-alpha-cholestane, 2-beta, 5-oxido-A-nor-5-beta-cholestane and 2-alpha-ethyl-2-beta,2'-oxido-A-nor-5-alpha-cholestane

Treatment of 2β-tosyloxy-A-nor-5α-cholestane-5-ol ( 2 ) with t-butoxide in t-butanol gave 2α, 5-epoxy-A-nor-5α-cholestane ( 3 ) in quantitative yield. When A-nor-5β-cholestane-2α, 5-diol ( 4 ) was treated with tosyl chloride in pyridine 2β-chloro-A-nor-5β-cholestane-5-ol ( 7 ) and 2α-tosyloxy-A-nor-5β-cholestane-5-ol ( 8 ) were obtained. Whereas the chloride 7 was resistant to t-butoxide the tosylate 8 was transformed into an 1 : 1 mixture of 2α, 5-epoxy-5β-cholestane ( 10 ) and 2ξ-t-butoxy-A-nor-5β-cholestane-5-ol ( 11 ). In 2α-tosyloxy-A-nor-5α-cholestane-5-ol ( 12 ) substitution occurred as the only reaction. Both oxetanes 3 and 10 isomerize after heating above 50° and in polar or protic solvents to form A-nor-Δ³⁽⁵⁾-cholestene-2α-ol ( 6 ) and -2β-ol ( 14 ) respectively. Also, 2, 5-diols are encountered. 2α-Ethyl-2β, 2′-epoxy-A-nor-5α-cholestane ( 23 ) was synthesized starting from A-nor-5α-cholestane-2-one ( 17 ). The intermediates were the ester 16 , the diol 18 , the hydroxy-tosylate 19 and the chlorhydrin 20 . The spirocyclic oxetane 23 was reduced by LiAlH₄ in dioxane (not in ether). By chromatography on silica gel 23 was isomerized to the homoallylic alcohol 21 and transformed into 2-methylene-A-nor-5α-cholestane ( 24 ) by fragmentation. The IR. and NMR. spectra of the new oxetanes were compared with those of a series of known oxetanes.     

The cyclobutane dimers of 2'-deoxyuridine, 2'-deoxycytidine, 5-methyl-2'-deoxycytidine and 5-bromo-2'-deoxyuridine

Irradiation of DNA and RNA pyrimidine nucleosides with UV light in frozen aqueous solution or in solution with acetone often results in the formation of cyclobutane dimers (CBDs). Many of these photodimers have not been characterized. We present here the results of work designed to achieve the isolation, spectroscopic characterization and determination of the stereochemical nature of a number of little studied or previously unstudied CBDs of four 2'-deoxyribonuclesides. These nucleosides are 2'-deoxyuridine (dUrd), 2'-deoxycytidine (dCyd), 5-methyl-2'-deoxycytidine (5-MedCyd) and 5-bromo-2'-deoxyuridine (5-BrdUrd). In particular, we have isolated and characterized six dUrd CBDs, five dCyd CBDs, five 5-MedCyd CBDs and four 5-BrdUrd CBDs. Photoproducts were studied by UV spectroscopy, mass spectrometry, proton NMR spectroscopy and via chemical approaches. Also presented are results from less definitive studies of a number of (6-4) (or 5-4) photoadducts of these nucleosides. In addition, results from exploratory photochemical studies of other 2'-deoxyribonucleosides in frozen solution, as well as some mixtures of two nucleosides, are given. The latter results indicate that 5-iodo-2'-deoxyuridine (5-IdUrd), 5-bromo-2'-deoxycytidine and 5-iodo-2'-deoxycytidine each form putative CBDs and that 5-BrdUrd is capable of forming putative mixed CBDs and (6-4) and/or (5-4) adducts with thymidine (Thd); 5-IdUrd similarly forms a (6-4) (or (5-4)) adduct with Thd.     

Conversions of 5-hydroxy-5, 6-dihydro-4H-1, 2, 5-oxadiazines

Oxidation of 5-hydroxy-5, 6-dihydro-4H-1, 2, 5-oxadiazines leads to the formation of 6H-1,2, 5-oxadiazine-5-oxides. Acid treatment of 5, 6-dihydro-4H-1, 2, 5-oxadiazines and 6H-1, 2, 5-oxadiazine-5-oxides results in heterocyclic-ring contraction with the formation of imidazole 3-oxides and 1-hydroxyimidazole 3-oxides. The structures of the products are established by their spectral properties and confirmed by independent synthesis.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1264–1266, September, 1970.     

Das Verhalten von Oxin, 2-Methyl-oxin, 5-Nitroso-oxin und 2-Methyl-5-nitrosooxin

Ohne Zusammenfassung     

An efficient synthetic approach towards new 5, 5'-diaryl-2, 2'-bipyridine-based fluorophores

An efficient approach has been developed for the synthesis of 5,5'-diaryl-2,2'-bipyridines via their 1,2,4-triazine analogues. The notable advantages of the present method are:The possibility of varying the aromatic substituents in the positions 5 and 5' of bipyridine core and the possibility for obtaining 2,2'-bipyridines bearing a fused cyclopentene core to increase the solubility in organic solvents. These 5,5'-diaryl-2,2'-bipyridines exhibited an intense emission in a range of ca. 422-521 nm in acetonitrile solution; depending on the nature of the aromatic substituents and the presence of annulated cyclopentene fragments. Apart from that, the significant bathochromic shifts of the both absorption and emission maxima were observed in comparison with a number of previously described similar structures. In some cases the significant increasing of the fluorescence quantum yields took place.     

A Synthesis of 2, 2-Ethylenedioxy-5-ketones

A straightforward, two-step preparation of the monoprotected 1, 4-diketones, 2, 2-ethylendioxy-5-ketones is presented.     

Synthesis of 5H-1, 2-dihydro-2, 5-dioxochromeno [2,3-b] pyridines

Some representative 5H-1,2-dihydro-2,5-dioxochromeno[2,3-b]pyridines have been prepared by condensation of 2-isocyanatochromone (obtained by Curtius rearrangement of the azide of chromone-2-carboxylic acid) with enamines, followed by cyclization.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 588–589, May, 1970.     

5-Methyl-2-furylglyoxal, 5-Methyl-4-nitro-2-furylglyoxal, and Their Derivatives. Nitration of 2-(5-Methyl-2-furyl)quinoxaline

The oxidation of 2-acetyl-5-methyl-4-R-furans (R = H, NO₂) by selenious acid was studied. Derivatives substituted at the C=O groups of the corresponding glyoxals were obtained. The nitration of 2-(5-methyl-2-furyl)quinoxaline was carried out at C_(4'). Oxidative splitting of the -nitrofuryl group occurs at the C₍₄₎-C₍₅₎ and C₍₅₎-O bonds.     

Substituted pyridines. 2, 5-diaroyl-4-phenylpyridines and 2, 5-diamino-4-phenylpyridines

2, 5-Dibenzoyl(di-p-toluoyl, di-p-anisoyl)-4-phenylpyridines, 2, 5-dimethyl-4-acetyl(propionyl)phenylpyridine N-oxides, and 2, 5-diamino-4-phenylpyridine have been obtained.     

The synthesis and photoactivated cytotoxicity of novel 5-phenyl-3- （2,2＇：5＇,2″-terthien-5-yl）-4,5-dihydro-lH-pyrazolines

A series of novel 5-phenyl-3-（2,2＇：5＇,2″-terthien-5-yl）-4,5-dihydro-lH-pyrazolines were synthesized in this report. Their photoactivated cytotoxicities on the 5podoptera litura （SL） cell line were evaluated using the MTT method. It was noticed that the inhibitory activities of all the conjugates was enhanced when irradiated with UV-A light. Compounds 4, 6 and 8 were found to be most effective with inhibition rates of 88.1%, 88.0%, and 90,5%, respectively, For compound B, the inhibition rate value was only slightly enhanced under the irradiation treatment （78.3%） compared to the dark treatment （74.8%）. The relationship analysis between structure and activity showed that the middle thiophene ring played an important role on the inhibitory activities. It was shown that these compounds could be the potential candidates for new photoactivated pesticides.     

Pentafluoronitrosulfane, SF5NO2

The synthesis of pentafluoronitrosulfane, SF5NO2, is accomplished either by reacting N(SF5)3 with NO2 or by the photolysis of a SF5Br/NO2 mixture using diazo lamps. The product is purified by treatment with CsF and repeated trap-to-trap condensation. The solid compound melts at -78 degrees C, and the extrapolated boiling point is 9 degrees C. SF5NO2 is characterized by 19F, 15N NMR, IR, Raman, and UV spectroscopy as well as by mass spectrometry. The molecular structure of SF5NO2 is determined by gas electron diffraction. The molecule possesses C2v symmetry with the NO2 group staggering the equatorial S-F bonds and an extremely long 1.903(7) Angstroms S-N bond. Calculated bond enthalpies depend strongly on the computational method: 159 (MP2/6-311G++(3df)) and 87 kJ mol(-1) (B3LYP/6-311++G(3df)). The experimental geometry and vibrational spectrum are reproduced reasonably well by quantum chemical calculations.     

The preparation,characterization and reactivity of the cyclometallosilane,cyclo-1,1-di-h5-cyclopentadienyltitana-2,2,3,3,4,4,5,5,-octaphenylpentasilane, (h5-C5H5)2TiSi(C6H5)2[Si(C6H5)2]2Si(C6H5)2

Titanium has been incorporated into a catenated silicon ring by means of the salt elimination reaction of dichlorodi-h⁵-cyclopentadienyltitanium(IV), (I), with 1,4-dilithiooctaphenyltetrasilane, Li₂Si₄(C₆H₅)₈, to yield the title compound (II). II was characterized as a cyclometallopolysilane by means of elemental analyses, base catalyzed hydrolyses, molecular weight determination, infrared and ¹H NMR spectroscopy. Electronic spectral data and electrochemical data are also discussed and support the formulation of II as a disubstituted (h⁵-C₅H₅)₂Ti^IV derivative. The reactivity of II, with CHCl₃, is described in terms of a radical decomposition pathway.     

5,5′-双(4-甲基苯基)-2,2′-联恶唑的晶体结构及构象

芳香取代恶唑是一类优良的有机萤光体,如1,4-双(5-苯基恶唑-2-基)苯(简称POPOP)可作为闪烁剂或激光染料使用。作者在前文中曾报道了一系列5,5′-双(取代苯基)-2,2′-联恶唑(1)的合成(简称POOP),它们也具有良好的激光性能。本文报道(1a,R=R′=4-CH_3)的晶体结构,并辅以分子力学法(MM-X程序)计算,探讨了POOP分子的基态构象。