Intramolecular Alkylation of Aromatic Compounds XXXVI [1]. Stereoselective Synthesis of C/D-cis-Configured Ergolines

Summary.  The stereoselective synthesis of cis-ergoline is presented. Starting from rac-N-benzoyl tryptophan methyl ester, the key compound indolinylmethylpyridin-3-one was prepared via a seven-step reaction in good yield. Since its cyclization to the desired ergolinone failed, the key compound was reduced to yield the two diastereomeric pyridin-3-ols; only one of them cyclized in trifluoromethanesulfonic acid, affording cis-ergoline. Catalytic hydrogenation of the latter gave N,N′-dimethyldihydroergoline, the X-ray crystallography of which revealed both the correct structure and identical relative configurations at C-5a and C-6a (SS or RR). Hydroboration and subsequent perruthenate oxidation of the Δ⁹-ergoline provided access to the regioisomeric ergolinols and ergolinones. Received December 27, 2001. Accepted January 15, 2002     

Abbildungseigenschaften der arithmetischen Mittel der geometrischen Reihe

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Zwei kleine analytische Kunstgriffe

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Ueber das Verh?ltniss zwischen Glycerin und Alkohol im Bier

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Über Faserschädigungen beim Bleichen

Zusammenfassung Es wird dargelegt, da? durch eine systematische Auswertung der Erkenntnisse der Faserforschung Fasersch?digungen beim Bleichen weitgehend vermieden werden k?nnen. An Hand einer Reihe von Untersuchungen wird über Fasersch?digungen durch Katalyse berichtet. Dazu wird vorgeschlagen, solche Fasersch?digungen durch Aufstellung entsprechender Gütebedingungen an das Kunstfasermaterial noch weitgehender auszuschalten. Vortrag, gehalten auf der Arbeitstagung des Instituts für Kunstfaserforschung der Technischen Hochschule München am 24. 3. 1944.     

Very Low Energy Electrons Transform the Cyclobutane‐Pyrimidine Dimer into a Highly Reactive Intermediate

Electrons with virtually no kinetic energy (close to 0 eV) trigger the decomposition of cytotoxic cyclobutane‐pyrimidine dimer (CPD) into a surprisingly large variety of fragment ions plus their neutral counterparts. The response of CPD to low energy electrons is thus comparable to that of explosives like trinitrotoluene (TNT). The dominant unimolecular reaction is the splitting into two thymine like units, which can be considered as the essential molecular step in the photolyase of CPD. We find that CPD is significantly more sensitive towards low energy electrons than its thymine building blocks. It is proposed that electron attachment at very low energy proceeds via dipole bound states, supported by the large dipole moment of the molecule (6.2 D). These states act as effective doorways to dissociative electron attachment (DEA).