Enantioselective Intermolecular Formal [3 + 3] Cycloaddition of 2,3-Disubstituted Indoles with Acrolein

An expedient enantioselective synthesis of highly substituted hydrocarbazoles has been realized by an organocatalyzed formal [3 + 3] cycloaddition between acrolein and 2,3-disubstituted indoles. Tricyclic hydrocarbazoles were obtained from a broad range of 2,3-disubstituted indoles and acrolein in good to excellent yields and excellent enantioselectivites

Enantioselective Synthesis of Indoloquinolizidines via Asymmetric Catalytic Hydrogenation/Lactamization of Imino Diesters

We have developed a highly efficient cascade sequence for asymmetric synthesis of indoloquinolizidines with absolute control of <i>cis</i>-H2/H12b relative geometry in good to excellent yields and excellent enantioselectivities. This cascade was triggered by the Ru­(II)–TsDPEN-catalyzed asymmetric transfer hydrogenation of imino diesters, with subsequent spontaneous lactamization with discrimination between the two diastereotopic 2-alkoxy-2-oxoethyl groups. The synthetic utility of this strategy was demonstrated by the asymmetric preparation of dihydrocorynantheol, geissoschizol, and isogeissoschizol