Ringerweiterung unter Lactonisierung von methylierten 1-(3′-Hydroxypropyl)-2-oxocyclododecan-1-carbonitrilen

Ring Enlargement by Lactonization of Methylated 1-(3′-Hydroxypropy1)-2-oxocyclododecane-1-carbonitriles The title compounds were prepared by Michael reaction of 2-oxocyclododecane-1-carbonitrile ( 1 ) and acrylaldehyde and its derivatives followed by NaBH₄ reduction or methylation of the aldehyde group with [(CH₃)₂Ti(i-PrO)₂] (Scheme 1). In all cases, the ring enlargement was performed with Bu₄NF/THF to give different methylated derivatives of 12-cyano-15-pentadecanolide ( 13 ) in 95–99% yield. The Yields of the rearrangement products are not dependent on the positions and numbers of the CH₃ groups in the side chain of 3 . The lactonization reaction is of unremarkable stereoselectivity.     

Synthese von 12-Cyano-15-hexadecanolid durch Ringerweiterung von 1-(3′-Hydroxybutyl)-2-oxocyclododecan-1-carbonitril

Synthesis of 12-Cyano-15-hexadecanolide by Ring Enlargement of 1-(3′-Hydroxybutyl)-2-oxocyclododecane-1-carbonitrile In the presence of Bu₄NF, 2-oxocyclododecane-1-carbonitrile ( 1 ) reacted with acrylaldehyde to form the corresponding aldehyde 2 which was methylated, e.g. with CH₃ Ti[OCH(CH₃)₂]₃. The resulting 1-(3′-hydroxybutyl)-2-oxocyclododecane-1-carbonitrile ( 5 ) was converted to 12-cyano-15-hexadecanolide ( 6 ) in nearly quantitative yield under the influence of Bu₄NF.     

Some criteria for the applicability of synthetic standards for laser spectral analysis of refractories

Summary The applicability of a series of synthetic standards for laser local analysis of refractories has been determined on the basis of 4 criteria: homogeneity, equality of the form and size of the craters formed by the laser beam, densities and plasma clouds. The validity of these criteria has been checked by comparison of the results received by electrone microprobe area scanning and by shooting the same places with a laser beam and reading the results with the help of synthetic standards.

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Kriterien zur Anwendbarkeit synthetischer Standards für die Laser-Spektralanalyse von feuerfesten Materialien

Zusammenfassung Die Anwendbarkeit von synthetischen Standards für die Laser-Lokalanalyse von feuerfesten Materialien wurde auf Grund von 4 Kriterien beurteilt: Homogenität, Gleichheit von Form und Größe der vom Laserstrahl verursachten Krater, Dichten und Plasmawolken. Die Gültigkeit dieser Kriterien wurde durch Vergleich der erhaltenen Ergebnisse mit den mit Hilfe der Elektronenmikrosonde erzielten Resultaten geprüft.

     

Synthesis of trans-Non-4-EN-2-Ynoic Acid

The synthesis of the title compound has been achieved from 1 -methoxybutenyne in 77% yield in three steps. A reaction mechanism is given to explain exclusive formation of 4,5-trans-configuration.     

Lacton-Bildung durch Ringerweiterung unter Alkalimetall-halogenid-Katalyse

Lactone Formation by Ring Enlargement Catalyzed by Alkali-Metal Halogenides In the presence of alkali-metal or tetraalkylammonium halogenides, 1-(3′-hydroxypropyl)-2-oxocyclododecane-1-carbonitrile ( 1 ) underwent ring enlargement to give 12-cyanopentadecan-15-olide ( 2 ). In DMF solution, the halogenides catalyzed this reaction, the influence of more basic anions being more pronounced. The rearrangement was strongly influenced by H₂O: in the presence of, e.g., 10 equiv. of H₂O, it was nearly blocked. On boiling in pure solvent, 1 was rearranged thermally to 2 .     

Ringerweiterung durch Fragmentierung. Synthese von 15-Pentadecanolid (Exaltolid®)

Ring Enlargement by Fragmentation. Synthesis of 15-Pentadecanolide (Exaltolide®) The title compound was synthesized from 1-(3′-hydroxypropyl)-2-oxocyclododecane-1-carbonitrile ( 3 ), using two different routes (Scheme). The CN group of 3 was converted to the Me₃N⁺ residue in 5 which underwent, upon NaH treatment, a fragmentation leading to the ring-enlargement product 6 . The same product was observed after heating the ring-enlarged dimethylamine oxide 14 , prepared from 3 by Bu₄NF treatment and conversion of the CN into the dimethylamine-oxide moiety. Ozonolysis of the methylidene double bond in 6 and reduction of the resulting C = O to a CH₂ group gave Exaltolide® ( 8 ).     

Eine neue Synthese von (±)-Dihydrorecifeiolid

A New Synthesis of (±)-Dihydrorecifeiolide Ethyl 1-(2′-formylethyl)-2-oxocyclooctane-1-carboxylate ( 2 ) prepared by Michael reaction of ethyl 2-oxocyclooctane-1-carboxylate ( 1 ) was regioselectively methylated at the aldehyde group with (CH₃)₂Ti[OCH(CH₃)₂]₂ to give 3 (Scheme 1). The alcohol 3 was treated with Bu₄NF to give the deethoxycarbonylated product 4 which by distillation gave the bicyclic enol ether 5 . Oxidation (m-chloroperbenzoic acid) of 5 and reduction of the resulting oxolacton 6 yielded the title compound (±)-dihydrorecifeiolide ( 7 ) in an overall yield of nearly 50 %. Methylation of the aldehyde 2 with MeLi gave the ring-enlarged lacton 9 in poor yield (13 %). The deethoxycarbonylation reaction 3 → 4 was studied in more detail (Scheme 3).