NMR (1H, 13C) and MO (ab initio, CNDO/2, EHT) studies on basic and N-protonated hydrazinecarbothioamide

The conformational preferences of hydrazinecarbothioamide (HCTA, H2NNHCSNH2) in its basic and N-protonated (PHCTA, H3NNNHCSNH2) forms have been studied by 1H and 13C NMR spectroscopy and by theoretical LCAO-MO methods (ab initio, CNDO/2 and EHT). The hindered rotation around the C---N bond has been investigated by a total line shape analysis for the thioamide protons and by the three MO methods. Changes in the molecular conformation and electronic structure on protonation are briefly discussed.

Co-2-Ions In A Low-Pressure Glow-Discharge Of Carbon-Dioxide

$CO_2^{-}$ ions have been detected in the gas phase and measured by a mass spectrometer with a flight time of 30 µs in the positive column of carbondioxide glow discharge.

Studies in terpenoids. Part 42. Synthesis of 3-(2-hydroxyisopropyl)5,8-dimethyl-1,2-naphthoquinone (emmotin-H)

Emmotin-H, a naturally occurring sesquiterpenoid 1,2-naphthoquinone pigment (1) has been synthesised in a four step sequence starting from the known 5,8-dimethyl-4-oxotetralin-2-carboxylic acid (3a). Selenium dioxide oxidation of its methyl ester (3b) gives 3-methoxycarbonyl-5,8-dimethyl-1,2-naphthoquinone (4) which on reductive acetylation affords the corresponding diacetoxynaphthalene ester (5). Its reaction with excess of methylmagnesium iodide is accompanied by aerial oxidation during work-up and furnishes emmotin-H (1).

Crystal structures of 1,4-diaza bicyclo[2.2.2.]octane and N,N-dimethyl formamide adducts of copper acetate

The crystal structures of copper acetate adducts with 1,4-diaza bicyclo [2.2.2.]octane and N,N-dimethyl formamide are shown to be dimeric with Cu---Cu distances of 2.633 Å and 2.616 Å respectively.

Vilsmeier reaction on some 6- and 7-methoxy-1- and 2-tetralones.

Vilsmeier reaction on a few representative 6- and 7-methoxy-1- and 2-tetralones has been investigated. While 1-tetralones give the corresponding 1-chloro-2-formyl3, 4-dihydronaphthalenes, the 2-tetralones afford 1,3-bisformyl-2-chloronaphthalenes. Spectral characteristics of all the products obtained are given and a mechanistic proposal has been made to explain the observed chlorobisformylation.

Dialkyl (3-Aryl- 1,2,4-oxadiazol-5-yl)phosphonates: Synthesis and Thermal Behavior-Evidence for Monomeric Alkyl Metaphosphate

Dialkyl (3-aryl-l,2,4-oxadiazol-5-yl)phosphonate6sa -h have been obtained by 1,3-dipolar cycloaddition of arenenitrile oxides 5a-f to dialkyl phosphorocyanidates (4a and 4b) in yields ranging between 30% and 58%. A standardized method for obtaining cyanidates 4a and 4b has been established. The diethyl thiophosphorocyanidate (4c) is less reactive than 4a and 4b, only the 3-(4'-nitrophenyl) derivative 6i being obtainable. While the IR and NMFt spectra of 6a-i were unexceptional, their UV spectra showed evidence of conjugative interaction in high degrees between the phosphonate and heterocyclic moieties as well as a varying conjugative interaction between the heterocyclic and aryl moieties. The oxadiazoles 6a-h are thermally labile and yield trialkyl phosphates 7 as the only identifiable products. A mechanism based on the intermediacy of monomeric alkyl metaphosphate 11 in the formation of trialkyl phosphate was postulated, and supportive evidence in the form of trapping the metaphosphate with acetophenone has been obtained.

Structure Of 5'-Deoxy-5',6-Epithio-5,6-Dihydro-2',3'-O-Isopropylideneuridine, C12h16n2o5s

Mr=300.33 , triclinic, P1, a=5.635 (2), b=11.077(2), c=11.582(2)A, a= 70.48 (1), fl= 88.16 (3), y=80.56(3) ° , V= 670.325 A3, Z=2, D x = 1.49 Mg m -3, Cu Ka, n= 1.54184 ,A, g = 2.308mm -1, F(000)=316, T=301K, R=0.054, R w = 0.093 for 1944 observed counter reflections. The sulphur position with respect to the dihydrouracil ring, which is of possible relevance to the action of thymidylate synthetase, is axial in molecule A and equatorial in B. Both molecules show the anti conformation about the glycosidic bond [torsion angle C(6)-N(1)-C(1')-O(4'), 2'CN = 21.6 (9) and 29.4 (10) °] and have the C(4')-endo, O(4')-exo (40T) sugar conformation. The dioxolane-ring conformation is O(2')-endo in A and C(7)-endo in B. The dihydrouracil rings show self base pairing with hydrogen bondsN(3A)...O(ZB) and N(3B)...O(ZA).

Structural studies of analgesics and their interactions .10. A hydrated 1-1 complex between niflumic acid and ethanolamine, c13h8f3n2o-2.c2h8no+.h2o.

Mr= 361.3, triclinic, P1, a = 6-239 (2), b=11.280(2), c=12-451(2)A, a=101.2 (1), B= 92.3 (1), 7=99.9(1)°, V=844.123 A3, Z=2, Dx= 1.42, D m = 1.42 (1) Mg m -3, n(Cu Ka) = 1.5418 ,A., g = 1-102 mm -1, F(000) = 376, T= 293 K. Final R = 0.064 for 2150 observed reflections. The niflumic acid anions consist essentially of three planar groupings, namely, two six-membered rings and a carboxylate group attached to one of them. The invariant common structural features observed in the crystal structures of fenamates, namely, the coplanarity of the carboxyl group and the six-membered ring bearing it, and the internal hydrogen bond between the carboxyl group and the imino N atom that bridges the two sixmembered rings, are retained in the complex. The amino N atom is gauche with respect to the terminal hydroxyl group in the ethanolamine cation. The complexation between the two molecules is achieved through ionic and hydrogen-bonded interactions involving the carboxylate group in niflumic acid.

A polarized, twisted, ethylene: structure of methyl 2-(1,3-dimethyl-2-imidazolidinylidene)-3-oxobutyrate dihydrate, C10H16N2O3.2H2O

Mr = 248, monoclinic, P21/n, a = 12.028 (2), b=7.168(2), c= 15.187(5)A, fl=91.88(2) °, Z= 4, V= 1308.6,~3, Din= 1.26, Dx= 1.263 Mgm -3, 2 (Cu Ka) = 1.5418 .A, g = 0.86 mm -1, F(000) = 536, T= 293 K. Final R = 5.6% for 2120 observed reflexions. Owing to the push-pull effect, the C=C bond distance is as long as 1.464 (2)/k with the twist angle about the bond 62.6.

Structure of a thionucleoside: 5'-deoxy-5',6-epithio-5,6-dihydro-2',3'-O-isopropylidene-3-methyluridine

C13HlsN205 S, M r = 314.35, orthorhombic, P212121 with a = 39.526 (4), b = 6.607 (2), c = 5.661 (2) A, Z = 4, V = 1478.36 A 3, D c = 1.412 Mg m -3, Cu Ka radiation. Final R = 0.073 for 1154 observed counter reflections. The sulphur atom is in a pseudo-equatorial position with respect to the dihydrouracil ring. The sugar pucker is predominantly O(l')-exo unlike the C(3')-exo,C(4')-endo observed for 2',3'-O-isopropylideneuridine (ISPU). The fivemembered dioxolane ring has C(7) displaced by 0.497 (7)A from the best plane through atoms 0(2'), C(2'), C(3'), 0(3'), in contrast to ISPU where 0(3') shows the maximum deviation.

Zeeman effect of chlorine nuclear quadrupole resonance and hydrogen bonding in 2,6-, 2,5- and 3,5-dichlorophenols

The Zeeman effect of chlorine nuclear quadrupole resonance in polycrystalline samples of 2,6-, 2,5 and 3,5-dichlorophenol has been investigated at room temperature in order to study the effect of hydrogen bonding on the electric field gradient asymmetry parameter n. While the two n.q.r. lines in 3,5-dichlorophenol gave an asymmetry parameter of 10%, those in 2,6- and 2,5-dichlorophenol gave different values of n for the two chlorines. The chlorine atom which is ortho to the OH group and involved in hydrogen bonding (i.e., corresponding to the low frequency line) gave an asymmetry parameter of 0.21 in 2,6-dichlorophenol and 0.17 in 2,5-dichlorophenol while the other chlorine (i.e., corresponding to the high frequency line) gave a lower value of 0.12 in 2,6-dichlorophenol and 0.11 in 2,5-dichlorophenol. These values of n are discussed in terms of hydrogen bonding and bond parameters.

Tie-2 regulates the stemness and metastatic properties of prostate cancer cells

Ample evidence supports that prostate tumor metastasis originates from a rare population of cancer cells, known as cancer stem cells (CSCs). Unfortunately, little is known about the identity of these cells, making it difficult to target the metastatic prostate tumor. Here, for the first time, we report the identification of a rare population of prostate cancer cells that express the Tie-2 protein. We found that this Tie-2High population exists mainly in prostate cancer cell lines that are capable of metastasizing to the bone. These cells not only express a higher level of CSC markers but also demonstrate enhanced resistance to the chemotherapeutic drug Cabazitaxel. In addition, knockdown of the expression of the Tie-2 ligand angiopoietin (Ang-1) led to suppression of CSC markers, suggesting that the Ang-1/Tie-2 signaling pathway functions as an autocrine loop for the maintenance of prostate CSCs. More importantly, we found that Tie-2High prostate cancer cells are more adhesive than the Tie-2Low population to both osteoblasts and endothelial cells. Moreover, only the Tie-2High, but not the Tie-2Low cells developed tumor metastasis in vivo when injected at a low number. Taken together, our data suggest that Tie-2 may play an important role during the development of prostate tumor metastasis.

A 1h And 13c Magnetic Resonance And Infrared Spectroscopic Study Of Coordinated 2-Aminocyclopentene-1-Dithiocarboxylic Acid And Its S-Methyl Ester

The ligating properties of 2-aminocyclopentene-1-dithiocarboxylic acid and its S-methyl esters were investigated. Complexes with Zn(II), Cd(II) and Hg(II) halides were synthesized and characterized by infrared and proton and carbon-13 NMR studies. The results are concordant with a bidentate coordination of the -CS2 group to the metal ions