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Synfacts 2009(4): 0443-0443  
DOI: 10.1055/s-0028-1088101
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart ˙ New York

Brønsted Acid-Thiourea Co-Catalysis

Contributor(s): Benjamin List, Lars Ratjen
R. S. Klausen, E. N. Jacobsen*
Harvard University, Cambridge, USA
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Publikationsverlauf

Publikationsdatum:
23. März 2009 (online)

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Significance

The thiourea-1 Brønsted acid co-catalyzed Pictet-Spengler reaction of various tryptamines and aldehydes is reported. The authors assume the transformation to proceed via Brønsted acid supported Brønsted acid catalysis (I). After formation of an iminium ion intermediate, the enantioselective, chiral counteranion-assisted ­cyclization occurs. Subsequent rearomatization liberates the product and the catalysts.