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An organocatalyzed one-pot Michael addition and Pictet-Spengler sequence utilizing b-keto amide and aliphatic a,bunsaturated aldehydes was developed, which provided access to highly substituted indolo[2,3-a]quinolizidines as a mixture of keto and enol tautomers. Such tautomeric pairs were transformed into stable compounds with an E-ethylidenyl group in telescoped steps. This method was successfully applied in the synthesis of epi-geissoschizol. [ABSTRACT FROM AUTHOR]

An expedient diastereoselective synthesis of highly functionalized indolo[2,3-α]quinolizidines adopting a cisH2/H12b geometry has been realized by a Pictet−Spengler/lactamization cascade sequence. The absolute stereochemistry at C2, C3, and C12b was governed by the originally created chirality of the Michael adduct through organocatalyzed conjugate addition of dialkyl malonates to α,β-unsaturated aldehydes. [ABSTRACT FROM AUTHOR]