C2-Symmetric Cyclic Selenium-Catalyzed Enantioselective Bromoaminocyclization

A catalytic asymmetric bromocyclization of trisubstituted olefinic amides that uses a C-2-symmetric mannitol-derived cyclic selenium catalyst and a stoichiometric amount of N-bromophthalimide is reported. The resulting enantioenriched pyrrolidine products, which contain two stereogenic centers, can undergo rearrangement to yield 2,3-disubstituted piperidines with excellent diastereoselectivity and enantiospecificity.