A new family of phosphinthiourea catalysts was developed for the highly enantioselective synthesis of 2-aryl-2,5-hydropyrroles via a [3 + 2] cycloaddition of an electron-deficient allene with aryl and heteroaryl diphenylphosphinoylimines. The presence of both H(2)O and Et(3)N as additives was found to be important for achieving optimal rates. Dual activation of both nucleophile and electrophile by the bifunctional catalyst is invoked to account for the observed high reactivity and enantioselectivity.
Nucleophilic Addition toN-Phosphinylimines by Rare-Earth-Metal Triflate/Trifluoroacetic Anhydride Activation
作者:Winnie W. Ong、Aaron B. Beeler、Sarathy Kesavan、James S. Panek、John A. Porco