Enantioselective Pictet-Spengler Reaction of Nitrones Derived from <i>N</i><sub>b</sub>-Hydroxytryptamine with Aldehydes Catalyzed by Chiral Brønsted Acid-Assisted Lewis Acids
The enantioselective Pictet-Spengler reaction catalyzed by chiral binaphthol-derived Brønsted acid-assisted Lewis acids is demonstrated. The Pictet-Spengler reaction of nitrones, prepared from N b-hydroxytryptamine with aldehydes, gave the corresponding 1-substituted-2-hydroxytetrahydro-β-carbolines with up to 91% ee.
The Pictet–Spengler reaction of nitrones and imines prepared from N-hydroxytryptamine and tryptamine gave the corresponding tetrahydro-β-carbolines in excellent yields in the presence of Yb(OTf)3–TMSCl in a mixture of CH2Cl2 and THF.
enantioselective Pictet-Spengler reaction is demonstrated. Using diisopinocampheylchloroborane as a chiralLewis acid catalyst, the Pictet-Spengler reaction of N(b)-hydroxytryptamine with aldehydes gave the corresponding 2-hydroxytetrahydro-beta-carbolines in up to 90% ee. The enantioselective Pictet-Spengler reaction catalyzed by chiral binaphthol-derived Brønsted acid-assisted Lewis acids, with up to 91% ee