Michael-type aldehydes, -4-imidazolidinone

The amino-acid-derived imidazolidinones, so-called MacMillan catalysts, efficiently form iminium ions with a, 3-unsaturated aldehydes and catalyze a Friedel-Crafts-type Michael reaction. Based on this strategy, Hanes-sian and co-workers reported on a practical asymmetric synthesis of indole derivative (S)-(—)-14, which is a precursor of drug prototype (S)-(+)-15, a candidate for treatment of migraine headaches (Scheme 27.2). In this synthesis, nitrogen-containing aldehyde 11 was able to react with 5-bromoindole 10 in the presence of (/ ,/ )-MacMillan catalyst 12 to give the adduct 13 in quantitative yield with 92% ee. 

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