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Free keywords:
enamine catalysis; mechanism; organocatalysis
Abstract:
The isolation and structural characterization of both aldehyde- and ketone-derived proline enaminones are reported and discussed. Crystal structures of 10 proline enamines provide information on stereochemical aspects, i.e., double bond configuration and syn- vs. anti-positioning of the carboxylate relative to the enamine double bond. Furthermore, the obtained crystal structures are compared with the density functional theory-calculated structures of the ground and transition state and the postulated Seebach–Eschenmoser transition state.