Asymmetric reactions merging organocatalysis and metal catalysis significantly broaden the scope of organic synthesis.N evertheless,t he accomplishment of stereoselective annulations combining two types of dipole species,i ndependently generated from the activations of organocatalysts and metal complexes,s till remains as ac hallenging task. Now, Morita-Baylis-Hillman carbonates from isatins and carbamate-functionalized allyl carbonates could be chemoselectively activated by achiral Lewis basic tertiary amines and chiral iridium complexes.T he zwitterionic allylic ylides and 1,4-pallyliridium dipoles formed in situ are assembled in ah ighly stereoselective [4+ +3] annulation pattern. Similar cooperative catalytic strategy could be applied for the reactions of Morita-Baylis-Hillman carbonates and vinyl aziridines,furnishing an asymmetric [3+ +3] annulation reaction also with excellent stereocontrol. Scheme 1. Lewis base and transition-metal activations trategies for MBH derivatives and cooperative catalysis.
The Rauhut‐Currier reaction generally employs α,β‐unsaturated carbonyl compounds and nitroalkenes as the substrates. Here we develop an enantioselective formal [4+2] annulation reaction, which is initiated by an intermolecular cross Rauhut‐Currier reaction between electron‐deficient ortho‐formyl‐styrenes and 2‐benzoyl‐acrylonitriles catalyzed by an L‐phenylglycine‐derived phosphine, followed by a cascade aldol/acyl transfer/elimination process. A series of enantioenriched dialin frameworks with an unusual exo‐double bond are furnished in fair to good yields with moderate to excellent enantioselectivity, and the architectures with higher molecular complexity can be constructed via simple transformations.
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