A high-performance liquid chromatography method for determination 2-(n-(N,N,N-trimethyl)-n-alkyl)-5-alkylfuryl halides in dipalmitoylphosphatidilcholine liposome solutions

A high-performance liquid chromatography (HPLC) method for the determination of 2-(4-(N,N,N-trimethyl)-butyl)-5-dodecylfuryl bromide (DFTA) in dipalmitoylphophatidil-choline (DPPC) liposome solutions has been developed. Lipid-soluble furan derivatives, 2,5-disubstituted with different n-alkyl chains and a terminal trimethylammonium group are useful probes for studying singlet oxygen dynamics and equilibria in microcompartmentalized systems. The actual HPLC method uses a gradient elution and DAD detection. The chromatographic separation of these components is achieved using a C18 analytical column with a 10mM solution of 1-heptanesulfonic acid (PIC-7)-methanol (10:90, v/v) as initial mobile phase. Both DFTA peaks are well resolved and free of interference from matrix components and reaction products. The method has been found to be linear (r > 0.999) over a wide concentration range and reliable to perform kinetic experiments in which the time dependent consumption of a tetraalkylammonium surfactant in a microorganized systems composed by lipidic surfactants is followed.     

Fourier transform infrared spectra and molecular structure of 5-methoxytryptamine,N-acetyl-5-methoxytryptamine and N-phenylsulfonamide-5-methoxytryptamine

5-Methoxytryptamine (5-MT) is a potent antioxidant and has radioprotective action. N-acetyl-5-methoxytryptamine (melatonin, NA-5-MT) is a free radical scavenger and antioxidant, which protects against oxidative damage due to a variety of toxicants. The infrared spectra of 5-MT, NA-5-MT and new synthesized N-phenylsulfonamide-5-methoxytryptamine (PS-5-MT) were investigated in the region between 4000 and 400 cm(-1). Vibrational assignments of the molecules have been made for fundamental modes on the basis of the group vibrational concept, infrared intensity and comparison with the assignments for related molecules. X-ray powder diffraction patterns of molecules were also recorded. In order to optimize the geometries of the molecules, molecular mechanic calculations (MM3) were performed. Conformational analysis of 5-MT, NA-5-MT and PS-5-MT was also established by the using PM3 method.     

Enthalpies of formation of gas-phase N3, N3-, N5+, and N5- from Ab initio molecular orbital theory, stability predictions for N5(+)N3(-) and N5(+)N5(-), and experimental evidence for the instability of N5(+)N3(-)

Ab initio molecular orbital theory has been used to calculate accurate enthalpies of formation and adiabatic electron affinities or ionization potentials for N3, N3-, N5+, and N5- from total atomization energies. The calculated heats of formation of the gas-phase molecules/ions at 0 K are DeltaHf(N3(2Pi)) = 109.2, DeltaHf(N3-(1sigma+)) = 47.4, DeltaHf(N5-(1A1')) = 62.3, and DeltaHf(N5+(1A1)) = 353.3 kcal/mol with an estimated error bar of +/-1 kcal/mol. For comparison purposes, the error in the calculated bond energy for N2 is 0.72 kcal/mol. Born-Haber cycle calculations, using estimated lattice energies and the adiabatic ionization potentials of the anions and electron affinities of the cations, enable reliable stability predictions for the hypothetical N5(+)N3(-) and N5(+)N5(-) salts. The calculations show that neither salt can be stabilized and that both should decompose spontaneously into N3 radicals and N2. This conclusion was experimentally confirmed for the N5(+)N3(-) salt by low-temperature metathetical reactions between N5SbF6 and alkali metal azides in different solvents, resulting in violent reactions with spontaneous nitrogen evolution. It is emphasized that one needs to use adiabatic ionization potentials and electron affinities instead of vertical potentials and affinities for salt stability predictions when the formed radicals are not vibrationally stable. This is the case for the N5 radicals where the energy difference between vertical and adiabatic potentials amounts to about 100 kcal/mol per N5.     

Infrared spectra of seeded hydrogen clusters: (paraH2)N - OCS, (orthoH2)N - OCS, and (HD)N - OCS, N = 2 - 7

Infrared spectra of hydrogen-carbonyl sulfide clusters containing paraH2, orthoH2, or HD have been studied in the 2060 cm(-1) region of the C-O stretching vibration. The clusters were formed in pulsed supersonic jet expansions and probed using a tunable infrared diode laser spectrometer. Simple symmetric rotor type spectra were observed and assigned for clusters containing up to N = 7 hydrogen molecules. There was no resolved K structure, and Q-branch features were present for orthoH2 and HD but absent for paraH2. These characteristics can be rationalized in terms of near symmetric rotor structures, very low effective rotational temperatures (0.15 to 0.6 K), and nuclear spin statistics. The observed vibrational shifts were compared with those from recent observations on the same clusters embedded in helium nanodroplets. The observed rotational constants for the paraH2 clusters are in good agreement with a recent quantum Monte Carlo simulation. Some mixed clusters were also observed, such as HD-HD-He-OCS and paraH2 - orthoH2 - OCS.     

Synthesis of N4-(5-methoxy-7-benzofuranyl)-1,4-pentanediamine,an oxygen isostere of primaquine

N⁴-(5-Methoxy-7-benzofuranyl)-1,4-pentanediamine, an oxygen isostere of primaquine was synthesized and found devoid of antimalarial activity.     

Uridylyl-(5′→N)- serines

Russian Chemical Bulletin -     

1,4,7,10-N,N,N,N.四(2-(4-(2-乙酰硫基乙氧基)苯氧基)乙基)-1,4,7,10-四氮杂环十二烷的合成研究

以对苄氧基苯酚为原料,经3步反应合成不对称的对苯二酚烷氧基化合物,并以此为原料,合成乙酰硫基修饰的cyclen四取代氢醌醚链化合物.该路线不仅反应条件温和,操作易行,且收率高,克服了文献报道的合成路线重复性差、收率低的缺点.关键中间体及目标化合物经~1H NMR、~(13)C NMR、MS、IR和元素分析表征.     

5-(N-2-羟乙基)羟乙酰氨基-N,N′-双(2,3-二羟丙基)-2,4,6-三碘-1,3-苯二甲酰胺的合成

5-氨基-N,N′-双(2,3-二羟丙基)-2,4,6-三碘-1,3-苯二甲酰胺(2)在N,N-二甲基乙酰胺中可直接与乙酰氧基乙酰氯反应,产物再经碱性水解得5-羟乙酰氨基-N,N′-双(2,3-二羟丙基)-2,4,6-三碘-1,3-苯二甲酰胺(3),后者再与氯乙醇反应生成5-(N-2-羟乙基)羟乙酰胺基-N,N′-双(2,3-二羟丙基)-2,4,6-三碘-1,3-苯二甲酰胺(1),经乙二醇甲醚/正丁醇重结晶,纯度高于99%(HPLC),反应总收率由39.3%(文献值)提高到55.1%.     

Regioselective Deprotection of 1,3-Dibenzyl-5-(N,N-dimethylamino)-6-phenylethyluracil

The deprotection of 1,3-dibenzyl-5-(N,N-dimethylamino)-6-phenyl-ethyluracil I was investigated.A practical,regioselective N3 deprotection of compound I was performed with excellent yield using cyclohexene as a hydrogen donor.     

6α-取代的(1S, 7aS)-(+)-1-叔丁氧基-7a-甲基-2, 3, 5, 6, 7, 7a-六氢茚-5- 酮的合成

用化学动力学控制的方法在化合物3的5-C上C=O与6-C发生烯醇化生成锂盐,然后可在6-C位分别引入甲基、烯丙基、苄基、溴以及羟基取代基。产物6、7、8、9a和11经鉴定,除9α外其他都是α和β构型的混合物,其中以α-构型取代物为主。