Beilstein J. Org. Chem.2021,17, 1952–1980, doi:10.3762/bjoc.17.128
starting material in the asymmetric organocatalyzed reaction, the Enders group described the use of (S)-proline as catalyst in an intramolecular aldol reaction, enabling a new strategy to obtain coumarin natural products [34]. As for example, the total synthesis of (+)-smyrindiol (17), a linear
cascade reaction.
Total synthesis of (+)-smyrindiol (17).
Michael addition of 4-hydroxycoumarin (1) to enones 2 through a bifunctional modified binaphthyl organocatalyst 18.
Michael addition of ketones 20 to 3-aroylcoumarins 19 using a cinchona alkaloid-derived primary amine catalyst 22.
Enantioselective
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Graphical Abstract
Figure 1:
Coumarin-derived commercially available drugs.
Beilstein J. Org. Chem.2012,8, 1112–1117, doi:10.3762/bjoc.8.123
Dieter Enders Jeanne Fronert Tom Bisschops Florian Boeck Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany 10.3762/bjoc.8.123 Abstract The first organocatalytic asymmetric synthesis of smyrindiol, by using an (S)-proline catalyzed enantioselective
intramolecular aldol reaction as the key step, is described. Smyrindiol was synthesized from commercially available 2,4-dihydroxybenzaldehyde in 15 steps, with excellent stereoselectivity (de = 99%, ee = 99%). In the course of this total synthesis a new and mild coumarin assembly was developed.
Keywords: aldol
reaction; asymmetric synthesis; organocatalysis; proline; smyrindiol; Introduction
Furocoumarins are a group of compounds that are structurally derived from psoralen or angelicin (Figure 1) [1]. Naturally occurring furocoumarins are mainly found in plants of the Apiaceae and Rutaceae families [2] and are