Labdane diterpene glycosides with 6-deoxy-L-idose from Aster spathulifolius Maxim.

Three labdane type diterpene glycosides ($\text{1}$, $\text{2}$ and $\text{3}$) with 6-deoxy-L-idose have been isolated from Aster spathulifolius Maxim. and their structures have been determined on the basis of chemical and spectral data.     

New polyoxygenated steroidal glucosides from chrysolina hyperici (coleoptera : chrysomelidae)

Two new polyoxygenated steroidal glucosides ($\text{1}$ and $\text{2}$) have been isolated from the defensive secretion of C. hyperici and their structures have been determined by spectroscopic and chemical methods.     

The chemistry of phenalenium systems XXXIII. The Dibenzo[de;thi]naphthacenyl dication and the dianon

The dibenzo[de;hi]naphthacenyl dication ($\text{4}$) and dianion ($\text{5}$) have been generated from a mixture of the corresponding precursor hydrocarbons. The pmr spectra of $\text{4}$ and $\text{5}$ indicated that the positive and the negative charges were found to be fully delocalized over the molecules, respectively, consistent with the C_2v-symmetry structures. The pmr chemical shifts of $\text{4}$ correlate well with the Hückel charge densities.     

Generation and cycloaddition reactions of indole-2,3-quinodimethanes

N-methyl and N-tert-butoxycarbonylindole-2,3-quinodimethanes ($\text{2}$ and $\text{3}$) have been generated and observed to undergo intermolecular cycloaddition reactions with dienophiles.     

Benzo-separated pyrazolopyrimidines: Expeditious syntheses of [3,4-g]-and [3,4-h]-linked pyrazoloquinazolinones

Syntheses for pyrazolo[3,4-g]quinazolin-8(7H)-one ($\text{8}$) and its [3,4-h]-analog 11 have been developed involving elaboration of aminoindazolcarboxylic acids $\text{15}$ and $\text{30}$ from correspondingly substituted methylnitroindazols, and subsequent anellation of the pyrimidine ring by v. Niementowski cyclization.     

Structure of laurycolactone A and B,new C18 - quassinoids from Eurycoma longifolia and revised structured of Eurycomalactone (X - ray analysis)

Laurycolactone A $\text{2}$ and B $\text{3}$ are new quassinoids with a C₁₈ basic skeleton isolated from the Vietnamese Simaroubaceae, Eurycoma longifolia Jack. The structure of Eurycomalactone, a C₁₉ quassinoid isolated previously from the same plant, has been revised and shown to be $\text{4}$. The structures have been established by spectral means and those of $\text{2}$ and $\text{4}$ confirmed by X-ray diffraction analysis.     

Ichthyotoxic sesterterpenoids from the neo guinean sponge carteriospongia foliascens

Six 20,24-dimethylscalarane derivatives ($\text{5}$, $\text{12}$, $\text{15}$, $\text{17}$, $\text{19}$, and $\text{21}$) have been isolated from the Neo Guinean sponge Carteriospongia foliascens. Compound $\text{12}$ is identical with a C₂₇ tetracyclic terpene previously isolated from an Australian specimen of the same sponge. The five other derivatives are new and their structures have been established on the basis of their spectral data. The structure of $\text{5}$ was confirmed by single-crystal X-ray diffraction and that of $\text{15}$ by chemical correlation with $\text{12}$. The configuration at C-4 for all these compounds has been determined through ¹³C NMR data. Evidence leading to reverse the configuration at this centre in previously reported C₂₇ tetracyclic terpenes is discussed. An ecological function is suggested for these molecules.     

Über reaktionen mit aluminiumalkylen: XVII. Spektroskopische untersuchungen von komplexen aus butanoliden und äthylaluminium-verbindungen

Three different types of butanolide complexes with Et_nAlCl_3?n in the molar ratios $\text{1}\text{1}$ and $\text{1}\text{2}$ have been investigated by IR with ^1M NMR spectroscopy. The butanolides form $\text{1}\text{1}$ and $\text{1}\text{2}$ complexes with ethylaluminium halides, but with triethylaluminium only $\text{1}\text{1}$ complexes are formed. The complexes are intermediates in the cleavage of butanolides.     

Absolute stereostructures of halenaquinol and halenaquinol sulfate,pentacyclic hydroquinones from the okinawan marine sponge xestospongia sapra, as determined by theoretical calculation of CD spectra

The absolute stereostructures of two pentacyclic hydroquinones, halenaguinol ($\text{1}$) and halenaquinol sulfate ($\text{2}$) from the Okinawan marine sponge Xestospongia sapra, have been determined by means of theoretical calculation of CD spectra.     

Microwave-optical double resonance in molecular ions. Co+

Microwave—optical double resonance signals have been detected in a mass-selected ion-beam spectrometer for ¹²C¹⁶O⁺. With the optical excitation of fluorescence from the R₁ ($\text{1}\text{2}$) line of the (0,0) band of the A²Π_{$\text{3}\text{2}$} ← X²∑ transition of 20350.6 cm^?1, the microwave resonances occurred at 118101.8 ± 0.2 MHz and at 117694 ± 2 MHz corresponding to the N= 1, J = $\text{3}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ and the N = 1, J = $\text{1}\text{2}$ ← N = 0, J = $\text{1}\text{2}$ transitions.     

Nephelauxetic effect in some lanthanide(III) complexes with 2-pyridineamidoxime

Diffuse reflectance spectra of tris-(2-pyridineamidoximato) lanthanide(III) chlorides, [Ln(PAO)₃] Cl₃, Ln = Pr, Nd, Sm, Eu, Dy and Ho, in the visible region have been recorded for the first time. Shifts (100–150 cm^?1) of their f ? f transitions have been observed towards lower wave numbers in relation to the lanthanide aquoions. These data have been used for evaluation of the nephelauxetic ratio β′ and the covalency parameters b^{$\text{1}\text{2}$}. Sublevels with J = 0 and J = $\text{1}\text{2}$ as well as hypersensitive bands, obeying the selection rules|ΔJ|?2,|ΔL|?2, have been considered. The results have been discussed in terms of weak covalent bonding between the lanthanide ion and the nitrogen atoms of the ligands.     

Wannier states of molecular impurity in a liquid rare gas

We have measured the vacuum ultraviolet absorption spectra of CH₃I in solid and in liquid krypton in the spectral region 2000–1450 Å. In both phases we have observed two Wannier series n(²E_{$\text{3}\text{2}$}) and n(²E_{$\text{1}\text{2}$}) up to n = 3. Information has been obtained concerning the features of the conduction band in a liquid rare gas.     

Hydrodynamic properties and conformation of molecules of para- and meta-isomers of polyoxyphenylbenzoxazoleterephthalamide

Translational diffusion and intrinsic viscosity in 96% H₂SO₄ have been investigated for 20 samples of the para-isomer of polyoxyphenylbenzoxazoleterephthalamide (PpOPhBT) and 17 samples of its meta-isomer (PmOPhBT). The Mark-Kuhn equations have been obtained. The equilibrium rigidity of macromolecules in solution, calculated by using the wormlike chain theory, was characterized for PpOPhBT by the length of the Kuhn segment $\text{A = 320}\text{A}\text{?}$, the number of monomer units in a segment s = 17 and the coefficient of hindrance to intramolecular rotation in the chain σ = 1.5. For PmOPhBT the corresponding values are: $\text{A = 96}\text{A}\text{?}$, s = 5.9 and σ = 1.6. Analysis of flexibility mechanisms was carried out for PpOPhBT and PmOPhBT chains in solution.     

Potential metabolites of carcinogenic aza aromatic hydrocarbons synthesis of K-region oxide,phenol and dihydrodiols of 7-methylbenz[c]acridine

The potential K-region metabolites, $\text{trans}$- and $\text{cis}$-5,6-dihydroxy-7-methyl-5,6-dihydrobenz[c]acridine, 5,6-epoxy-7-methyl-5,6-dihydrobenz[c]acridine and 5-hydroxy-7-methylbenz[c]acridine, of 7-methylbenz[c]acridine have been synthesised.     

Plectranthoic acid A & B, two new triterpenoids from Plectranthus rugosus

Two new triterpenoid acids, designated as plectranthoic acid A and plectranthoic acid B, have been isolated from P. rugosus and are characterised as (20-S)-3α-hydroxy-18α,19α-$\text{H}\text{-}$-urs-12-en-30β-oic acid and (14-S)-3α-hydroxy-18α, 19α $\text{H}\text{-}$-urs-12-en-27α-oic acid.     

A novel synthesis of carbacyclin analogs via a stereoselective introduction of 15α-hydroxy group

(+/-)-6,9α-Methanoprostaglandin I₃, ($\text{2}$) and (+/-)-5,6-dihydro-6,9α-methano-6β-prostaglandin I₃, ($\text{4a}$) have been synthesized using a new method for the stereoselective introduction of the 15α-hydroxy group via a stereoselective electrophilic addition of phenyl-sulfenyl chloride to the enol ether ($\text{6}$) and ($\text{23}$) respectively.     

X-ray study of Hg2Cl2Br2 and HgCl2HgBr2 reactions in solid state

The reactions (I) Hg₂Cl₂(s) + Br₂(g) and (II) HgCl₂(s) + HgBr₂(s) have been investigated by an X-ray method. Both the reactions yield two forms of the mixed halide HgClBr, designated as α-HgClBr and β-HgClBr. The cell parameters of the two are as follows:α-HgClBr: $\text{a = 6.196}\text{A}\text{?}$, $\text{b = 13.12}\text{A}\text{?}$, $\text{c = 4.37}\text{A}\text{?}$, z = 4, ? = 5.91 g/cm³. The powder pattern and cell parameters are similar to that of HgCl₂. Therefore it is probable that the chlorine atoms, in the linear halogenHghalogen molecules of HgCl₂ structure have been replaced by bromines, and since the radius of the bromine atom is larger than that of chlorine, the lattice is larger in this case.β-HgClBr: $\text{a = 6.78}\text{A}\text{?}$, $\text{b = 13.175}\text{A}\text{?}$, $\text{c = 4.17}\text{A}\text{?}$, z = 4, ? = 5.40. These parameters are the same as those reported in the literature for β-Hg(ClBr)₂, and its X-ray powder pattern is similar to HgCl₂. Therefore this phase also has linear halogenHghalogen molecules but the distribution of Cl and Br atoms is perhaps random.Heating the products (I) and (II) up to the melting point increases the amount of α phase and decreases the β phase, whereas crystallization increases the β phase. DTA study has supported the X-ray findings.     

A molecular orbital study of the cis-trans energy difference in glyoxal

The barrier to internal rotation around the C-C bond in glyoxal, and the energy difference between the cis and the trans form of the molecule have been estimated using (7,$\text{3}\text{4}$) and (9,$\text{5}\text{4}$) Gaussian basis sets including polarization functions. The predicted energy of the cis form relative the ground state trans form was found to be substantially higher (4.9–6.3 kcal mol^?1) than the experimental value of 3.2 kcal mol^?1.     

The influence of the orientation of the NO molecule upon the chemiluminescent reaction NO+O3→NO2*+O2

A beam of state-selected NO molecules (J = Ω = $\text{3}\text{2}$) has been produced by an electrostatic hexapole and has been collided with O₃ molecules in a scattering chamber. The E-field dependence of the chemiluminescent cross section, σ_hr, has been investigated and resulted in the determination of the M-dependence of σ_hr: σ_hr (M)/σ₀ = 1.192±0.009, 0.0848±0.015, 1.177±0.015, 0.783±0.009 for M = $\text{3}\text{2}$, $\text{1}\text{2}$, $\text{?1}\text{2}$ and $\text{?3}\text{2}$, respectively. Application of the Legendre expansion technique and the density matrix formalism provided a deconvoluted σ_hr(γ), for a single angle of attack γ of the NO axis, expressed in simple model functions with adjustable parameters. From this analysis it is concluded that chemiluminescence only occurs when cos γ ≈ 1, the “end-on-head” orientation of NO yielding ≈ 30% of all collected light, and when cos γ ≈ ?0.275, the “broad-side-tail” orientation of NO yielding the remaining 70%. The steric factors belonging to these reactive orientations have been estimated and are S₁ = 0.25±0.07 and S₂ = 0.40±0.09, respectively. The observed dependence of σ_hr has been confronted with the rules of Woodward and Hoffman. Although there are indeed two symmetries (bpl and cpl) correlating the electron orbitals of the reactants and the products, these rules do not lead to an explanation of the steric effects of the NO+O₃ reaction.     

Teurilene and thyrsiferyl 23-acetate, meso and remarkably cytotoxic compounds from the marine red alga laurencia obtusa (hudson) lamouroux

Two new cyclic ethers consisting of squalene carbon skeleton have been isolated from the red alga L. obtusa. The absolute stereostructure of teurilene ($\text{1}$) was elucidated by x-ray crystallographic method, and the structure of thyrsiferyl 23-acetate ($\text{2}$) was established from the spectral and chemical evidence.