Affiliation:
1. Institut für Organische und Makromolekulare Chemie, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
Abstract
Starting from acid chlorides, alkynes, tryptamines, and acryloyl chloride, 21 densely substituted tetrahydro-β-carbolines were prepared in a four-component, one-pot reaction. In this study, the aza-Michael addition step to generate intermediate enaminones was optimized in the presence of ytterbium triflate. Moreover, apart from acryloyl chloride, all reactants could be deployed in almost equimolar ratios, which increases the atom economy of the sequence. For mechanistic rationalization, the concluding aza-anellation was investigated by DFT calculations on potential intermediates and corresponding activation energies, revealing that the aza-anellation proceeds via ene reaction rather than via electrocyclization.
Subject
Industrial and Manufacturing Engineering
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