Auto‐tandem catalysis (ATC), in which a single catalyst promotes two or more mechanistically different reactions in a cascade pattern, provides a powerful strategy to prepare complex products from simple starting materials. Reported here is an unprecedented auto‐tandem cooperative catalysis (ATCC) for Morita–Baylis–Hillman carbonates from isatins and allylic carbonates using a simple Pd(PPh3)4 precursor. Dissociated phosphine generates phosphorus ylides and the Pd leads to π‐allylpalladium complexes, and they undergo a γ‐regioselective allylic–allylic alkylation reaction. Importantly, a cascade intramolecular Heck‐type coupling proceeds to finally furnish spirooxindoles incorporating a 4‐methylene‐2‐cyclopentene motif. Experimental results indicate that both Pd and phosphine play crucial roles in the catalytic Heck reaction. In addition, the asymmetric versions with either a chiral phosphine or chiral auxiliary are explored, and moderate results are obtained.
The catalytic diastereodivergent construction of stereoisomers having two or more stereogenic centers has been extensively studied. In contrast, the switchablei ntroduction of another stereogenic element, that is,Z/E configuration involving ap olysubstituted alkene group,i nto the optically active stereoisomers,h as not been recognized yet. Disclosed here is the pseudo-stereodivergent synthesis of highly enantioenriched tetrasubstituted alkene architectures from isatin-based Morita-Baylis-Hillman carbonates and allylic derivatives,u nder the cooperative catalysis of at ertiary amine and ac hiral iridium complex. The success of the switchable construction of the tetrasubstituted alkene motif relies on the diastereodivergent 1,3-oxo-allylation reaction between N-allylic ylides and chiral p-allyliridium complex intermediates by ligand and substrate control, followed by the stereoselective concerted 3,3-Cope rearrangement process.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Scheme 5. Mechanism study for the cascade 1,3-oxo-allylation and Cope rearrangement process.
Angewandte ChemieForschungsartikel 7153
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