Synfacts 2007(12): 1309-1309  
DOI: 10.1055/s-2007-991331
Organo- and Biocatalysis
© Georg Thieme Verlag Stuttgart · New York

Chiral Tetraaminophosphonium Salts: A New Catalyst Motif

Contributor(s): Benjamin List, Corinna Reisinger
D. Uraguchi, S. Sakaki, T. Ooi*
Nagoya University, Japan
Further Information

Publication History

Publication Date:
22 November 2007 (online)


Ooi and co-workers have introduced chiral tetraaminophosphonium chlorides of type 3 as catalysts of the asymmetric Henry reaction of a broad range of aldehydes 1 and nitroalkanes 2. The authors’ working hypo­thesis includes (1) the in situ generation of tri­aminoiminophosphorane 5 upon deprotonation of 3 with KOt-Bu. (2) Phosphorane 5 will subsequently deprotonate nitroalkanes 2. The resulting chiral phosphonium nitronate ion pair 6 benefits from hydrogen bonding and enables (3) a highly stereo­selective addition of aldehydes 1 in the final step. The ability of phosphonium salts 3 acting as hydrogen bonding donors via the N-H protons could be demonstrated by an X-ray crystal structure of one representative (Ar = Ph).