Duplex Stability of 7-Deazapurine DNA: Oligonucleotides containing 7-bromo- or 7-iodo-7-deazaguanine

The oligonucleotide building blocks, the phosphonates 1a, b and the phosphoramidites 2a, b derived from 7-iodo- and 7-bromo-7-deaza-2′-deoxyguanosines 3a, b were prepared. They were employed in solid-phase oligonucleotide synthesis of the alternating octamers d(Br⁷c⁷G-C)₄ ( 8 ) and d(I⁷c⁷G-C)₄ ( 9 ) as well as the homo-oligonucleotides d[(Br⁷c⁷G)₅-G] ( 11 ) and d[(I⁷c⁷G)₅-G] ( 12 ). The melting profiles and CD spectra of oligonucleotide duplexes were measured. The T_m values as well as the thermodynamic data were determined and correlated to the major-groove modification of this DNA. The self-complementary octamers 8 and 9 form more stable duplexes compared to the parent oligomer d(G-C)₄. The heteroduplex of d[(I⁷c⁷G)₅-G] ( 12 ) with d(C₆) is slightly destabilized (ΔT_m = ?12°) over that of d[(c⁷G)₅-G] with d(C₆). However, the complex of 12 with poly(C) is more stable than that of d[(c⁷G₅-G)] with poly(C).     

Sulfones of 7-silyl- and 7-germylcephalosporanates

7-Silyl- and 7-germylcephalosporanates in the form of a mixture of 7a and 7b stereoisomers were prepared by the interaction of hydrosilanes and a hydrogermane^* with sulfones of tert-butyl esters of 7-diazocephalosporanic acid and 7-diazodesacetoxycephalosporanic acid in the presence of rhodium diacetate. Some of the synthesized substances manifest cytotoxic effects in relation to tumor cellsin vitro, and also inhibit the catalytic activity of the enzyme elastase.Generic terms for compounds with the general formula HSiX₃ or HGeX₃-Translator.Latvian Institute of Organic Chemistry, Riga LV-1006, Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1504–1509, November, 1998.     

Synthesis of 7-hydroxythioridazine and 7-hydroxysulforidazine

The thioridazine metabolites 7-hydroxythioridazine (2a) and 7-hydroxysulforidazine (2b) were synthesized. Commercial 4-chloro-3-nitrophenylmethylsulfone was converted to the corresponding 4-thiol through an intermediate xanthate ester. Subsequent zinc metal reduction provided the 3-amino thiolate. This salt was condensed with chloroquinone to yield 7-hydroxy-2-methylsulfonylphenothiazine which was then protected as the isopropyl ether. N-Alkylation with 2-(2-chloroethyl)-1-methylpiperidine using sodium hydroxide, then ether cleavage, afforded 2b . The N-alkylation followed by reduction with diisobutylaluminum hydride and deblocking yielded 2a . These reference standards will assist in an exploration of the potential role of meta-bolically formed 2a and 2b in the neuroleptic response to thioridazine.     

Synthesis of 7-ethoxy- and 7-fluoro-phenothiazines

Synthesis of 7-ethoxy- and 7-fluoro-phenothiazines is reported by Smiles rearrangement of 5-ethoxy- and 5-fluoro-2-formamido-2′-nitrodiphenylsulfides. The later were obtained by the formylation of 2-amino-5-ethoxy/5-fluoro-2′-nitrodiphenylsulfides which were prepared by the condensation of 2-amino-5-ethoxy/5-fluoro-benzenethiols with o-halonitrobenzenes.     

Bridgehead substitutions. Preparation of 7-chloro-, 7-bromo- and 7-methylsulphinyl-gibberellins

7-Hydroxygibberellins react with nucleophiles in the presence of fluoroamine to give bridgehead substitution products.     

The O–H···O, O–H···N and C–H···O hydrogen bonds in 1,4-dimethylpiperazine mono-betaine monohydrate

1,4-Dimethylpiperazine mono-betaine (1-carboxymethyl-1,4-dimethylpiperazinium inner salt, MBPZ) crystallizes as monohydrate. The crystals are orthorhombic, space group Pccn. Two MBPZ molecules and two water molecules form a cyclic oligomer, (MBPZ·H₂O)₂. The O–H···O and O–H···N hydrogen bonds are of 2.769(1) and 2.902(1) Å, respectively. The dimers interact with the neighboring molecules through the C–H···O hydrogen bonds of 3.234(1) Å. The piperazine ring assumes a chair conformation with the N(4)–CH₃ and N⁺(1)–CH₂COO⁻ groups in the equatorial position and the N⁺(1)–CH₃ group in the axial one. The FTIR spectrum is compared with that calculated by the B3LYP/6-31G(d,p) level of theory.     

Laser Raman studies on compounds 7.O4O.7 and 7.O5O.7

Laser Raman studies on two compounds of the α,ω-bis(4-alkylanilinebenzylidene -4′-oxy)alkane series were carried out in the spectral regions 1140–1220 and 1550–1650 cm^-1 as a function of temperature. Compounds 7.O4O.7 and 7.O5O.7, exhibit SmA and SmF phases. The structural differences between these liquid crystal dimers, having either an odd or an even number of carbon atoms in the spacer, are remarkably existent in the room temperature Raman spectra. The results are rationalized on the basis of the tendency of these compounds to exhibit bent shapes, and how this manifests in the odd-even effect at the molecular level assuming a semi-rigid core region of the dimeric molecule. It is found that the behaviour of the odd spacer dimer (7.O5O.7) agrees with the molecular model, whereas the even spacer dimer (7.O4O.7) behaves in a similar fashion to monomeric compounds such as the nO.m. compounds. In both cases, dynamic changes around the C=N bond have a profound effect both on the molecular shape in the different phases and on phase behaviour.     

7-Hydroxy-neopinon-dimethylacetal

Zusammenfassung Durch Schütteln einer Lösung von 14-Brom-codeinon-dimethylacetal (1 b) in methanol. NaOH mit einem besonders vorbehandelten Hydrierungskatalysator an der Luft entsteht das bisher noch nicht beschriebene (7R)-7-Hydroxy-neopinon-dimethylacetal (6) (Ausb. 75%). Die Nebenprodukte7, 8, 9, 10a und10 b wurden durch präp.DC getrennt und in kristallisierter Form gewonnen. Ihre Struktur sowie die Konfiguration am C-7 wurde vor allem NMR-spektroskopisch ermittelt.

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7-Hydroxy-neopinone dimethyl acetal

The synthesis of (7R)-7-Hydroxy-neopinone dimethyl acetal (6) has been performed by shaking on air a solution of 14-bromo-codeinone-dimethyl acetal (1 b) in alcoholic NaOH in the presence of an especially prepared hydrogenation catalyst in 75% yield. The by-products7, 8, 9, 10a, and10b were isolated by preparative thin layer chromatography. The structures and the configuration on C-7 were established on the basis of NMR-spectroscopy.

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Herrn Prof. Dr.O. Hromatka zum 65. Geburtstag gewidmet.     

7-Lithio-norbornadiene

A synthesis of the title compound is described as well as its reactions with some electrophiles.     

7-Alpha-methylestrogens

The synthesis of the 7α-methyl homologues of estrone, estradiol, 17α-methyl- and 17α-ethinyl-estradiol, and of the respective 3-methyl ethers is described. Their estrogenic activity is compared with that of the corresponding unmethylated compounds.     

7-Brom-neopinon-dimethylketal-methoperchlorat

Zusammenfassung Thebain-metho-methylsulfat liefert mit Bromacetamid in absol. Methanol das Methosalz des 7-Brom-neopinon-dimethylketals (3 a) im Gegensatz zur Thebain-Base (1), die das isomere 14-Bromcodeinon-dimethylketal (2 a) ergibt. Aus dem Ketonmethoperchlorat3 b entstehen beim Erwärmen in Wasser oder gepufferter Lösung das Methoperchlorat des 7-Oxo-thebainons (6) und HBr. In stark saurer Lösung hingegen gelangt man von3 a oder3 b zu dem mit3 b isomeren 7-Brom-7,8-dehydrometathebainon-methoperchlorat (7 a). Von diesem ausgehend, wurden die Diketon-methoperchlorate8 a und8 b sowie das Methin9 gewonnen, weiters auch die entsprechenden Methylenolate10 a und10 b. Über7 a führte auch der Weg zu den 7-Brom-morphothebain-derivaten12 a–d und13.

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Synthesis and rearrangement reactions of 7-bromo-neopinone-dimethylketal methoperchlorate

Contrary to thebaine base (1), which on treatment with bromoacetamide in anhydrous methanol is known to give 14-bromocodeinone dimethylketal (2 a), thebaine metho methylsulfate yields the metho salt of the isomeric 7-bromoneopinone dimethylketal (3 a). From the ketone methoperchlorate (3 b) on heating with water or in buffered solution the methoperchlorate of 7-oxo-thebainone (6) and HBr are formed. However, in strongly acidic solutions3 a as well as3 b give 7-bromo-7,8-dehydrometathebainone methoperchlorate (7 a), isomeric with3 b, a key intermediate, from which the diketone methoperchlorates8 a and8 b, the methine9, the methyl enolates10 a and10 b, and finally the 7-bromo-morphothebaine derivatives12 a–d and13 can be obtained.

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Teile aus der Dissertation Univ. Wien 1965.     

Reaktionen der Cycloheptatrienylkomplexe [η7-C7H7W(CO)3]BF4 und η7-C7H7Mo(CO)2 Br mit Neutralliganden und die elektrochemische Reduktion des Wolframkomplexes

Reactions of the Cycloheptatrienyl Complexes [η⁷-C₇H₇W(CO)₃]BF₄ and η⁷-C₇H₇Mo(CO)₂Br with Neutral Ligands and the Electrochemical Reduction of the Wolfram Complex Compounds of the type [η⁷-C₇H₇M(CO)₂L][BF₄] (L = P(C₆H₅)₃, As(C₆H₅)₃, Sb(C₆H₅)₃ for M = W and L = N₂H₄ for M = Mo) were synthesized and characterisized. The iodide η⁷-C₇H₇W(CO)₂I reacts with the diphosphine ((C₆H₅)₂PCH₂)₂ to give the trihapto complex η³-C₇H₇ W(CO)₂I((C₆H₅)₂PCH₂)₂. In the case of η⁷-C₇H₇Mo(CO)₂ Br reaction with hydrazine leads to the substitution product [η⁷-C₇H₇ Mo(CO)₂N₂H₄]^⊕, which can be stabilized by large anions. The binuclear complex [C₇H₇W(CO)₃]₂ has been synthesized electrochemically.