0940 - 1020 Takashi Ooi

Molecular Design of Chiral Tetraaminophosphonium Salts and Their Unique Asymmetric Catalyses

Chiral organic ion pair catalysis occupies a unique place in the recent development of organic molecular catalysis. In this catalysis, the structural feature of cation has been regarded as the most important element for attaining high reactivity and selectivity. On the other hand, the anion part of the quaternary onium salts is certainly essential to neutralize the charge, but it hardly contributes to the overall reaction efficiency and/or stereoselectivity in the targeted transformation due to the intervention of the multiple ion-exchange processes. Thus, the synthetic relevance of incorporating tunable, functional anions to the original salts is yet to be explored. In this context, we have been interested in the possibility of establishing a new catalysis of chiral onium salts possessing an appropriate organic anion, which can be controlled not only by the structural modification of the cation but also by that of the initial anion through its continuous participation to the catalytic cycle [1]. In this lecture, I would like to present such asymmetric catalyses of P-spiro-type, designer chiral tetraaminophosphonium phenoxides 1 for achieving highly stereoselective conjugate addition of acyl anion equivalent (2-unsubstituted azlactone) to ,-unsaturated acylbenzotriazole [2], and also detail recent advances along this research stream.