Synthesis of the Wieland–Miescher ketone

The Wieland–Miescher ketone is one of the most widely used intermediates in steroid and terpene synthesis: it already contains two of the six-membered rings, an angular methyl group and two carbonyls that can be manipulated separately.

It is prepared by Robinson annulation of 2-methylcyclohexane-1,3-dione: Michael addition to methyl vinyl ketone, with a weak base, gives the triketone, which cyclizes by intramolecular aldol condensation with pyrrolidine as the catalyst. With (S)-proline one of the enantiomers is obtained (see chiral catalysis).