Rh-Catalyzed Asymmetric Hydroformylation of Heterocyclic OlefinsUsing Chiral Diphosphite Ligands. Scope and Limitations

摘要

We used a series of diphosphite ligands to study the effect of the ligand backbone, the length of thebridge, and the substituents of the biphenyl moieties and determine the scope of this type of ligand inthe Rh-catalyzed asymmetric hydroformylation of several hetereocylic olefins. By carefully selectingthe ligand components, we achieved high chemo-, regio-, and enantioselectivities in differentsubstrate types. Unprecedentedly high enantioselectivities for five-membered heterocyclic olefinswere therefore obtained. Note that both enantiomers of the hydroformylation products can besynthesized using the same ligand by a simple substrate change. For the seven-membered heterocyclicdioxepines, our results are among the best obtained. Also, both enantiomers of the hydroformylationproducts can be obtained by using pseudoenantiomer ligands or by carefully tuning the ligandparameters.