Über die Reaktion von Propiolsäure und Propiolsäureester mit Cyclohexanon

In the presence of potassium t-butoxide or potassium hydroxide, propiolic acid adds two molecules of cyclohexanone to form the isomeric seq-cis- and seq-trans-7, 14-Dioxa-dispiro[5.1.5.2]pentadec-15-yliden-acetic acids IIa and IIIa, respectively. Methyl propiolate and cyclohexanone react analogously in the presence of potassium t-butoxide, yielding the corresponding esters. The structure of these condensation products follows from their physical properties and from degradation reactions to known compounds.