Structural and conformational studies on euphornin and related diterpenes

In addition to euphornin, three new toxic substances (euphornins A, B and C) have been isolated from the plant $\text{Euphorbia}$$\text{helioscopia}$ L., and their absolute stereostructures also been elucidated on the basis of their spectral data and some chemical evidence together with an X-ray crystallographic analysis of the p-bromobenzoate derived from euphornin. Furthermore, their conformations have also been discussed.     

Condensed cyclic and bridged-ring systems : part 12: A novel synthetic route to 4-p-methoxyphenyl-bicyclo[ 2.2.2 ]octan-2-ones and some bicyclo [ 3.2.1 ] octane derivatives by acid-catalyzed intramolecula

The efficacy of a new acid-catalyzed intramolecular C-alkylation has been demonstrated by the synthesis of 1-methyl-4-$\text{p}$-methoxyphenylbicyclo [2.2.2] octan-2-one ($\text{5}$) and 4-$\text{p}$-methoxyphenylbicyclo [2.2.2] octan-2-one ($\text{6}$) from easily accessible starting materials. The carbinol $\text{20}$, derived from $\text{5}$, undergoes facile rearrangement leading to 1-$\text{p}$-methoxyphenyl-4-methyl bicyclo [3.2.1] oct-3-ene ($\text{22}$), which has been transformed to $\text{endo}$-1-$\text{p}$-methoxyphenyl-4-methylbicyclo [3.2.1] octan-3-one ($\text{25}$).     

Highly fluorinated heterocycles. Part XII. Some reactions of the heptafluoro-p-dioxanyl anion.

2$\text{H}$-heptafluoro-$\text{p}$-dioxan has been lithiated using methyl lithium in ether and thence converted to heptafluoro-p-dioxan-2-carboxylic acid (characterised as its anilinium and S-benzylthiouronium salts and methyl ester), 2-(heptafluoro-$\text{p}$-dioxanyl)propan-2-ol [dehydrated to 2-(heptafluoro-$\text{p}$-dioxanyl)propene], heptafluoro-$\text{p}$-dioxanyltrimethylsilane, and heptafluoro-2-iodo-$\text{p}$-dioxan. This last was converted to its Grignard reagent, and to bis(heptafluoro-$\text{p}$-dioxanyl)mercury, and was copper-coupled to trans-1-chloro-2-iodoethylene.Decomposition of heptafluoro-$\text{p}$-dioxanyl-lithium gave hexafluoro-$\text{p}$-dioxene. 2$\text{H}$-heptafluoro-$\text{p}$-dioxan, with KOH and formaldehyde, afforded hexafluoro-$\text{p}$-dioxanylmethanol.     

Partitioning of organic solutes between the micellar and the aqueous phase as studied with an artificial kidney

The partitioning of $\text{p}$-nitrophenyl acetae and of $\text{p}$-methylphenylsulfonylmethyl methanesulfonate into CTAB micelles in aqueous solution has been quantitatively investigated by means of a Cordis Dow C-Dak 1.30 artificial kidney.     

S)-(+)-2-(p-tolylsulfinyl)-2-buten-4-olide: an enantiomerically pure Michael acceptor for asymmetric synthesis of 3-substituted 4-butanolides. (—)-podorhizon.

A short, reliable, and practical synthesis of ($\text{S}$)-(+)-2-($\text{p}$-tolylsulfinyl)-2-buten-4-olide has been developed, and the utility of this Michael acceptor for highly enantiocontrolled synthesis of 3-substituted 4-butanolides has been demonstrated.     

A novel product from the reaction of p-methylbenzyl chloride with guanosine in neutral aqueous solution

An unanticipated product from reaction of guanosine with $\text{p}$-methylbenzyl chloride in neutral aqueous solution has been identified as 4-($\text{p}$-methylbenzyl)-5-guanidino-1-β-D-ribofuranosylimidazole.     

Magydardiendiol,diterpenoid with a new skeleton from magydaris panacifolia (umbelliferae).

Three new diterpenoids with a substituted α-cyclogeraniol skeleton have been isolated from the umbelliferae $\text{Magydaris panacifolia}$ (Vahl) Lange, for which the names of magydar-2,13-dien-11,17-diol, $\text{1}$, magydar-2,10 (20), 13-trien-17-ol, $\text{2}$, and magydar-2,10(20), 13-trien-17-yl acetate, $\text{3}$, are proposed. The structures of these substances have been deduced from spectroscopic and chemical data.     

Dirac—Fock one-centre calculations. The molecules BH,AlH, GaH,InH and TlH

Relativistic and non-relativistic Hartree—Fock calculations including np_{$\text{1}\text{2}$} and np_{$\text{3}\text{2}$} orbitals in the valence MO are reported for the molecules BH, AlH, GaH, InH and TlH. The relativistic contraction of the bond length reaches 7.0% for TlH. Relativistic effects make the chemical bond stronger for AlH, GaH and InH and weaker for TlH. The calculated force constants and dissociation energies are in reasonable agreement with experiment. A change from npσ towards np_{$\text{1}\text{2}$} bonding takes place along the series. For Tl the MO is only 39% p_{$\text{3}\text{2}$} as compared with the non-relativistic value of 67%. This probably explains the dominant monovalency of thallium.     

Per - bicyclophosphoranylation d'alditols

Reaction of bicyclophosphane $\text{1}$ with glycol $\text{2}$, glycerol $\text{3}$, erythritol $\text{4}$, L(-)arabitol $\text{5}$ and dulcitol $\text{6}$ leads to the corresponding per-alkoxybicyclophosphoranes $\text{2p}$ - $\text{6p}$ which are in tautomeric equilibrium with the phosphates forms $\text{2p}$′ - $\text{6p}$′.The amount of these latters increases regularly from traces to 24%.     

Evidence for N2N3N45 super coster kronig processes in metallic Nb,Mo, Ru and Rh

The 4p photoelectron spectra of metallic Nb, Mo, Ru and Rh have been recorded. By use of a deconvolution procedure it is shown that the 4p_{$\text{1}\text{2}$} spin-orbit component has a linewidth which significantly exceeds that of the 4p_{$\text{3}\text{2}$} component. This suggests that N₂N₃N₄₅ super Coster Kronig processes give a considerable contribution to the decay rata of the 4p_{$\text{1}\text{2}$} hole state.     

The total synthesis of i-oxygenated eudesmanolides

A route towards I-oxygenated eudesmanolides, via a (2+2) photocycloaddition reaction for constructing the decalin framework is described. The following natural substances have been synthesized. (=)-dihydroreynosin ($\text{1}$), (±)-1- oxo-dihydronmagnolialide ($\text{2}$), (±)-maritimin ($\text{3}$), (±)-dihydromagnolialide ($\text{4}$), (±)-magnolialide ($\text{5}$), (±)-dihydrosantamarine ($\text{6}$). Also a synthesis of (±)--santonin ($\text{7}$) is presented.     

Organomercury compounds XX Reactions of lithium polyfluorobenzenesulphinates with mercuric salts

The lithium polyfluorobenzenesulphinates, Li O₂SR (R = C₆F₅, $\text{p}$-HC₆F₄, $\text{m}$-HC₆F₄, or $\text{o}$-HC₆F₄), and the dilithium tetrafluorobenzenedisulphinates, $\text{p}$- and $\text{o}$-(LiO₂S)₂C₆F₄, have been prepared by reaction of the appropriate polyfluoroaryllithium compounds with sulphur dioxide. All compounds were isolated as hydrates and gave the corresponding $\text{S}$-benzylthiouronium salts on treatment with $\text{S}$-benzylthiouronium chloride. From reactions of the lithium sulphinates with suitable mercuric salts in water, generally at room temperature, the derivatives RHgX (R = C₆F₅, X = Cl, Br, CH₃CO₂, or PhSO₂; R = $\text{p}$-HC₆F₄, X = Cl, Br, or CH₃CO₂; R = $\text{m}$-HC₆F₄, X = Cl or Br; R = $\text{o}$-HC₆F₄, X = Cl), $\text{p}$-(XHg)₂C₆F₄ (X = Cl, Br, or CH₃CO₂), and $\text{o}$-(XHg)₂C₆X₄ (X = Cl or Br) have been prepared. Similarly, the bispolyfluorophenylmercurials R₂Hg (R = C₆F₅, $\text{p}$-HC₆F₄, or $\text{m}$-HC₆F₄) have been prepared from the corresponding lithium sulphinates and either mercuric salts or polyfluorophenylmercuric halides in aqueous $\text{t}$-butanol. A possible mechanism for the sulphur dioxide elimination reactions is discussed.     

Isotope effects in electron-donor-acceptor complexes involving aromatic hydrocarbons and fluoranil from NMR shift measurements

Equilibrium constants and NMR shift parameters have been determined for complexes of benzene, toluene and p-xylene and their perdeutero-analogues with fluoranil in cyclohexane solution from NMR shift measurements. Isotope effects are observed in the 1:1 equilibrium constants for the complexes of p-xylene $\text{(}\text{K}{}_1\text{(D)}\text{K}{}_1\text{(H)}$= 1.1₀) and toluene $\text{(}\text{K}{}_1\text{(D)}\text{K}{}_1\text{(H)}$ = 1.0₉). A much smaller effect was observed for the benzene complex which could not be quantified. These results may be interpreted through either the larger electronegativity of H over D, or the greater steric requirements of H over D.     

Chemistry of fluorinated quinones. Part II proton and fluorine nmr spectra

Proton and fluorine NMR spectra of nineteen fluorinated quinones are presented. Coupling constants were found for HH: $\text{o}$ 10.5, $\text{m}$ 2.2, $\text{p}$ ?0.3-0; for FF: $\text{o}$ 4.5–5.6, $\text{m}$ 0.3–1.7, $\text{p}$1.5–3.0; and HF: $\text{o}$ 8.2–10.1, $\text{m}$ 6.0–8.4, and $\text{p}$ 0.6–0.9.     

Identification of a new eicosanoid from in vitro biosynthetic experiments with clavularia viridis. Implications for the biosynthesis of clavulones.

A cell-free homogenate of $\text{Clavularia viridis}$ converts tritiated arachidonic acid into a new eicosanoid identified as $\text{4}$ (free acid) by chemical and chromatographic studies in comparison with synthetic substances. The isolation of $\text{4}$ suggests a novel, non-prostanoid type pathway for the biosynthesis of the clavulones.     

Mechanism of selective p-quinol formation in the cobalt schiff base complex-catalyzed oxygenation of 4-alkyl-2,6-di-t-butylphenols

The selective formation of $\text{p}$-quinols in the Co(Salpr)-catalyzed oxygenation of 4-alkyl-2,6-di-$\text{t}$-butylphenols in MeOH has been found to involve the rate determining reduction of peroxy-$\text{p}$-quinolato Co(III) complex formed in the initial fast step. An ionic mechanism of the reduction of the OO bond in the peroxy complex by MeOH has been discussed based on kinetic studies. The reactive species in the catalytic cycle is found to be [Co(III)(Salpr)(OH)].     

Synthesis and properties of p-C8-bridged hydroquinones and p-benzoquinones

The cycloaddition of the dispiro compound, $\text{2}$, with a variety of 1,3-butadienes affords diacetates of $\text{p}$-C₈-bridged hydroquinones, which are led to the corresponding hydroquinones and $\text{p}$-benzoquinones.     

A novel cycloaddition reaction of p-benzoquinones. Transannular cycloaddition in p-C8-bridged p-benzoquinones by way of an oxyallyl intermediate

The transannular cycloaddition between the double bond on the side chain and the $\text{p}$-benzoquinone ring in $\text{p}$-C₈-bridged $\text{p}$-benzo-quinones by way of an oxyallyl intermediate is described.     

Simultaneous degradation and cross-linking effect of dicumyl peroxide on ethylene-propylene copolymers

A study was made of the effect of dicumyl peroxide on proportions of the degradation (p) and cross-linking (q) in statistical ethylene-propylene copolymer. It was found that $\text{p}\text{q}$, according to the Charlesby-Pinner equation, depends mainly on the propylene content and not on other characteristics of the copolymer.     

Synthesis of three potential inhibitors of the biosynthesis of leukotrienes A–E

Simple synthetic routes are described to 5,6-dehydroarachidonic acid ($\text{5}$) $\text{cis}$-8-eicosen-5-ynoic acid $\text{6}$) and the thio analog of (±)-leukotriene A ($\text{7}$), which are of value in the study of inhibition of the biosynthesis of leukotrienes and slow reacting substances.