In Gegenwart von Phosphorsäure kondensieren die Chromanone und Thiochromanone (I) mit den Benzaldehyden (II) zu den Benzylidenchromanonen (III), die thermisch in Gegenwart einer sehr geringen Menge Piperidin zu den Benzylchromonen (IV) isomerisieren.

No abstract

Competitive α and β cyclization of 2‘-hydroxychalcone epoxides affords 2-(α-hydroxybenzyl)-3-coumaranone and/or 3-hydroxyflavanones, which depends on the conditions employed. Epoxidation of 2‘-hydroxychalcones by dimethyldioxirane followed by either base- or acid-catalyzed ring closure provides a novel, general, and efficient method for the synthesis of trans-3-hydroxyflavanones, which includes also the naturally occurring derivatives. Extension of this two-step procedure to 1-(2-hydroxyphenyl)-2-alken-1-ones was also accomplished. A strong preference for α cyclization was observed in the case of β-unsubstituted or -monoalkylated α,β-enones, while both 2,2-dimethyl-3-hydroxychromanones and 2-(1-hydroxy-1-methylethyl)-3-coumaranones were obtained from the β,β-dimethylated substrates.

Die Reaktion der Aminothiophenole (I) mit den Chalkonen (II), (IV) bzw. (VI) liefert je nach dem Substituenten in Ring Adie Propiophenone (III), sowie die Thiazepine (V) bzw. (VII).Erhitzen von (III) in methanolischer Lösung und in Gegenwart katalytischer Mengen Essigsäure ergibt die Thiazepine (VIII).

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