Download PDF
Synfacts 2007(11): 1208-1208  
DOI: 10.1055/s-2007-991240
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart · New York

Catalytic Asymmetric Pictet-Spengler Reaction via Sulfenyliminium Ions

Contributor(s): Benjamin List, Subhas Chandra Pan
M. J. Wanner, R. N. S. van der Haas, K. R. de Cuba, J. H. van Maarseveen, H. Hiemstra*
University of Amsterdam, The Netherlands
Further Information

Publication History

Publication Date:
23 October 2007 (online)

    Permissions and Reprints

Significance

The authors report a catalytic asymmetric Pictet-Spengler reaction of trypt­amine via a sulfenyliminium ion. Chiral phosphoric acid 1 was the best catalyst for this reaction and the N-tritylsulfenyl substituent on the tryptamine substrate was found to be essential for achieving high enantioselectivity and conversion. 3,5-Di(tert-butyl)-4-hydroxytoluene (BHT) acts as radical scavenger and prevents the decomposition of the product. The authors have removed the sulfenyl group under acidic conditions in one pot. With 5 mol% of catalyst 1 good to excellent yields (77-90%) and moderate to high enantioselectivities (er = 65:35 to 93:7) are obtained for different aldehydes.