Synthesis of Prenyl‐ and Geranyl‐Substituted Carbazole Alkaloids by DIBAL‐H Promoted Reductive Pyran Ring Opening of Dialkylpyrano[3,2‐a]carbazoles

The DIBAL‐H promoted reductive pyran ring opening of dialkylpyrano[3,2‐a]carbazoles provides a direct access to a broad range of prenyl‐ and geranyl‐substituted carbazoles. Formation of a pyran ring followed by reductive ring opening represents a new method for the introduction of prenyl and geranyl groups. In the course of the present work, we achieved the first total syntheses of the following eight carbazole alkaloids: clauraila‐E, 7‐hydroxyheptaphylline, 7‐methoxyheptaphylline, mukoenine‐B (clausenatine‐A), mukoenine‐A (girinimbilol), mahanimbinol (mahanimbilol), euchrestine‐A, and isomurrayafoline‐B.     

Magnetism under high pressure studied by 57Fe and 151Eu nuclear scattering of synchrotron radiation

The nuclear forward scattering (NFS) of synchrotron radiation is especially suited for probing magnetism at very high pressure, here in the Mbar range, by the nuclear resonances of ⁵⁷Fe and ¹⁵¹Eu. We report on high pressure (h.p.) NFS studies with the 14.4 keV transition of ⁵7Fe on magnetic RFe₂ Laves phases of cubic C15 structure (YFe₂, GdFe₂) and hexagonal C14 structure (ScFe₂, TiFe₂) at pressures up to 100 GPa (=1 Mbar). We present also h.p. NFS studies performed with the 21.5 keV resonance of ¹⁵¹Eu, probing the magnetism in the CsCl-type h.p. phase of EuTe. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthese makrocyclischer Lactone durch Ringerweiterung. Vorläufige Mitteilung

Synthesis of Macrocyclic Lactones by Ring Enlargement Reaction Treatment of 3-(1-nitro-2-oxocyclohexyl)propanal ( 1 ) prepared by Michael addition of 2-nitrocyclohexanon and acrylaldehyde with methyltri (2-propoxy)tita-nium yielded a mixture of 2 and 3 which was converted into 6-nitro-9-decanolide ( 4 ).     

A simple expression for the buffer index of a weak polyprotic acid

A simple expression for the buffer index of a solution containing a weak polyprotic acid is derived and presented.     

Laser dynamics and rotational relaxation in chemically formed carbon monoxide

Pulsed laser action from CS₂: O₂ is investigated. Numerical calculations of the pulse shapes of a large number of vibrational- rotational transitions are compared with experiments. The computations show that rotational relaxation determines to a wide extent the spectral and temporal output of the laser.