Unsymmetrical three-carbon condensations with dimedone

Condensing together equimolecular amounts of dimedone, an aldehyde, and s-aminocrotonic ester gives derivatives of 3-ethoxycarbonyl-2, 7, 7-trimethyl-5-keto-1, 4, 5, 6, 7, 8-hexahydroquinoline (IVa-c); of these, compounds IVb and IVc can be oxidized by chromic anhydride to 3-ethoxycarbonyl-2, 7, trimethyl-5-keto-5, 6, 7, 8-tetrahydroquinolines (Vb, c). The UV and IR spectra of compounds IVc and Vc are determined. Oxidation splits IVa to bisdimedonylmethane (VI).