Allylation and alkylation of oxindoleketimines via imine umpolung strategy

Enantioselective Benzylation and Allylation of a Crucial Synthon of 3-Amino Oxindole Schiff Base Promoted by a Cinchonidinium Phase Transfer Catalyst to Enable the Effective Preparation of Chiral Quaternary 3-Amino Oxindoles

3-Amino oxindole Schiff base has been used as an efficient and crucial synthon for highly enantioselective benzylation and allylation with benzyl bromides and allyl bromides in the presence of a 1,3-bis[O(9)-allylcinchonidinium-N-methyl]-2-fluorobenzene dibromide phase transfer catalyst under mild reaction conditions. A broad series of chiral quaternary 3-amino oxindoles were smoothly obtained in good to excellent yields with excellent enantioselectivities (up to 98% ee) with broad substrate generality. A typical scale-up preparation and subsequent Ullman coupling reaction were also smoothly performed, and a special and important chiral spirooxindole benzofuzed pyrrol scaffold with potential pharmaceutical and organocatalytic activities was successfully obtained.

Cobalt-Catalyzed Umpolung Alkylation of Imines To Generate α-Branched Aliphatic Amines

Here we report a general and mild approach to prepare α-branched aliphatic amines from imines. This method capitalizes on a cobalt-catalyzed umpolung alkylation of imines, employs easily available reaction partners, and demonstrates a broad substrate scope. Mechanistic studies suggest this transformation occurs by a radical pathway.

Iminophosphorane-mediated regioselective umpolung alkylation reaction of α-iminoesters

The first regioselective umpolung alkylation of α-iminoesters with alkyl halides mediated by iminophosphorane has developed (up to 82% yield).