Synfacts 2008(6): 0639-0639  
DOI: 10.1055/s-2008-1072762
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart · New York

Hydroamination of Nonactivated Alkenes

Rezensent(en):Benjamin List, Frank Lay
L. Ackermann*, A. Althammer
Georg-August-Universität Göttingen, Germany
Phosphoric Acid Diesters as Efficient Catalysts for Hydroaminations of Nonactivated Alkenes and an Application to Asymmetric Hydroaminations
Synlett  2008,  995-998  
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Publikationsverlauf

Publikationsdatum:
21. Mai 2008 (online)


Significance

A catalytic amount of Brønsted acid enables high yielding intramolecular hydro­aminations of electronically unactivated alkenes with basic amines. Screenings identified phosphoric acid 1 as the most active catalyst for this cyclo­isomerization. Substrates with ether, nitro, ester, or chloro functionalities are tolerated. By using enantiomerically pure phosphoric acid (R)-1a the authors show an unprecedented example of a metal-free asymmetric hydroamination of nonactivated alkenes, albeit with modest selectivity (er = 58.5:41.5).

Comment

This intramolecular addition of an amine to a C-C double bond depicts a direct and atom-economical access to N-heterocycles, which are ubiquitous in natural products as well as biologically active compounds. Most organocatalytic additions of N-nucleophiles to olefins require activation of the alkene functionality. The observed effectiveness of this addition might be due to the intramolecular nature of this cycloisomerization. A screening of different enantiopure phosphoric ­acids might result in higher enantiomeric ratios.