A biogenetically patterned total synthesis of prostaglandin E1

Methyl 11-tert-butyldimethylsilyloxyeicosa-8(Z), 12(E), 14(E)-trienoate was stereoselectively cyclized by treatment with Hg(OCOCF₃)₂ to give a properly functionalized PG skeleton, which was converted to PGE₁ in good over all yield.     

Quantitative thin-layer chromatographic determination of some prostaglandin-derivatives of the subgroups E2, A2 and B2

Summary A direct, quantitative, thin-layer chromatographic (TLC) method is described for the separation and determination of a PGE₂-descendant (compound I = PGE₂-desc.), a PGA₂-descendant (compound II = PGA₂-desc.) and a PGB₂-descendant (compound III = PGB₂-desc.) as pure substances and in pharmaceutical preparations. The extraction of the active ingredients is performed in a fully automated apparatus within 5 min. Using TLC compound I (UV-inactive substance) must be converted into compound III so that it can be measured at -max. 280 nm. Compound II can be measured both directly at -max. 224 nm and after conversion into compound III [1]. The conversion of PGE₂-desc. and PGA₂-desc. into PGB₂-desc. was achieved after spraying the separated PG-spots on the TL-plates with KOH solution and heated. The TLC development was carried out on silica gel 60 F₂₅₄ and measurement was direct on the plates by chromatogram spectrodensitometry using the reflection method. The method is also suitable for stability studies and has also proved useful in the analysis of the prostaglandin-derivatives in various pharmaceutical preparations.

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Quantitative dünnschicht-chromatographische Bestimmung einiger Prostaglandinderivate der Untergruppen E₂, A₂ und B₂

     

Synthesis of a novel prostaglandin H2(pgH2) analogue

We describe a five-step synthesis of a PGH₂ analogue from (R)-glyceraldehyde acetonide via formation of 1,2(S)-0-isopropylidene-hex-3(E)-en-5-one, conjugate addition of prostanoid C₁₃- C₂₀ side-chain as the cuprate with C₁-C₇ side-chain used to quench the resultant enolate, and finaily acid-catalysed ketal exchange to provide the desired analogue.     

A convenient route to (+)-(9,11)-epithia-(11,12)-methano-thromboxane A2, from prostaglandin E2, methyl ester

(+)-(9,11)-Epithia-(11,12)-methano-thromboxane A₂ which is of great importance in thromboxane research, has been synthesized from prostaglandin E₂ methyl ester.     

A stereoselective total synthesis of nat (−) prostaglandin E1 and its optical antipode

A stereoselective total synthesis of nat (?) prostaglandin E₁ and its optical antipode employing the Diels-Alder adduct oftrans-piperylene and maleic anhydride as starting material is described.     

Detection of the ππ* E2g state in sym-tetrafluorobenzene

The VUV absorption spectrum of gaseous 2,3,5,6-tetrafluorobenzene is reported up to its first IP. The absolute extinction coefficient and f value are given. A band appearing at 6.85 eV is attributed to the E_2g benzene parent state with f = 0.06. A similar band is found in 1,3,5-trifluorobenzene, where the E_2g ← A_1g transition is symmetry allowed.     

Synthesis of the sulfones of leukotriene C4, D4, and E4

A simple one-step preparation of the sulfones of Leukotriene C₄, D₄ and E₄ has been developed by the direct oxidation of the parent compounds. An alternative synthesis of these sulfones has also been carried out by reduction of an acetylenic precursor.     

Preparation and structure of a ruthenium dicarbonyl derivative of the P2N4S2 ring

The reaction of Ru(CO)₄(C₂H₄) or Ru(CO)₅ with 1,5-Ph₄P₂N₄S₂ in CH₂Cl₂/hexane at 23°C produces the dimer [Ru(CO)₂(Ph₄ P₂N₄S₂)]₂ (2), which was shown by X-ray crystallography to have a centrosymmetric structure in which the P₂N₄S₂ ring is attached to one ruthenium atom through two (geminal) nitrogen atoms and the remote sulfur atom and serves as a bridge to the other ruthenium atom via the second sulfur atom. Crystals of 2 ·2(CH₂Cl₂) are triclinic, space group P (No. 2), a = 12.901(1) Å, b = 13.072(1) Å, c = 10.123(1) Å, = 100.88(1)°, β = 98.90(1)°, γ = 67.50(1)°, V = 1542.4(3) Å, Z = 1 with final R and R_w values of 0.040 and 0.027, respectively.     

Synthesis of prostaglandin D1 and D2 via the three-component coupling process

Facile, convergent entries to prostaglandin D₁ and D₂ are outlined.     

Infrared studies of the diatomic molecules O2, N2, NO and H2 adsorbed on Fe2O3

An infrared spectroscopic study of the diatomic molecules O₂, N₂, NO and H₂ adsorbed under different conditions on Fe₂O₃ has been performed.Complex patterns of absorption on both α-Fe₂O₃ and γ-Fe₂O₃ activated in O₂ at high temperature are assigned to vibrations of two different chemisorbed O₂ species.N₂ molecules do not interact with “oxygen rich” α-Fe₂O₃ surfaces, but give N₂O^? and N₂O₂^2? species when chemisorbed on evacuated surfaces.NO molecules give complex patterns of absorption, depending on the gas pressure. Three different types of nitrate structures can be identified, as well as NO, NO^? and cis-N₂O₂ chemisorbed species. Chemisorbed water molecules are formed by contact of H₂ with Fe₂O₃ surfaces even at room temperature.