Addition von Aldehyden an aktivierte Doppelbindungen, XIV. Über die katalysierte Reaktion von Aldehyden mit Mannich‐Basen

Abstract

Alkalicyanid-und thiazoliumsalz-katalysierte Additionen von Aldehyden an Mannich-Basen von gesattigten und ungesattigten Ketonen fuhren zu 1,4-Diketonen (1 -6, 9-22). Addition of Aldehydes to Activated Double Bonds, XIV" The Catalysed Reaction of Aldehydes with Mannich BasesAlkali cyanide-and thiazolium salt-catalysed addition of aldehydes to Mannich bases of saturated and unsaturated ketones leads to the formation of 1,4-diketones (1 -6, 9-22).Bei der Herstellung von 1,4Diketonen durch katalysierte Addition von Aldehyden an u,p-ungesattigte Ketone lassen sich die ungesattigten Ketone auch durch Mannich-Basen ersetzen '). Aromatische und heterocyclische Aldehyde geben bei der cyanid-katalysierten Reaktion mit Mannich-Basen die entsprechenden 1,4-Diketone, wenn man in Dimethylformamid bei 35-100°C und mit 0.1 -1 Molaquiv. Natriumcyanid als Katalysator arbeitet. Mit Benzaldehyd wurden 1 -6 erhalten.

Thiamin-Diphosphate-Dependent Enzymes: New Aspects of Asymmetric CC Bond Formation

“…Other putative acceptor substrates known from nonenzymatic benzoin condensations and related reactions are Michael acceptors for the intermolecular (Scheme , entry 1)42 and intramolecular Stetter reaction (entry 2),43 diketosubstrates for ring‐closing reactions (entry 3),44 ketones (entry 4),45 Mannich bases (entry 5),46 and imines (entry 6) 47. Remarkably, in the last case the corresponding benzoins are not observed and do not serve as substrates either 47d.…”

Bicyclic Peroxides and Perorthoesters with 1,2,4‐Trioxane Structures

“…A straightforward approach to the required substrate was a Stetter reaction between 3-methylcrotonaldehyde and alkylvinyl ketones. [16] Dicarbonyl compounds 1 were selectively protected and reduced to allylic alcohols 3. Subsequent photooxygenation under solid-state conditions [17] Scheme 1.…”

Cyanide Anions as Nucleophilic Catalysts in Organic Synthesis

“…78 An illustrative example is the use of gramine (69) as a surrogate for an exo-methylene indole, which yields phenacylindole (70) (Scheme 19). 79 While cyanide is used as a catalyst in Stetter's original work in 1973, 80 he reported on the use of thiazolium salts in the presence of triethylamine as catalysts one year later in 1974. 81 The key advantage was that thiazolium-derived heterocyclic carbenes as catalysts were also suitable to con-…”

“…78 An illustrative example is the use of gramine (69) as a surrogate for an exo-methylene indole, which yields phenacylindole (70) (Scheme 19). 79…”