Construction Of Atropisomers Based On Pd/Norbornene-Cocatalyzed Cascade Reaction

This thesis mainly focused on a palladium/norbornene-cocatalyzed three-component cross-coupling for the highly efficient synthesis of biaryl atropisomers.The following two chapters were covered.In the first part,major improvements of the already known methods to build up such atrop isomers and recent developments concerning Catellani reaction were introduced.Catalyst-control led atropselective cross-coupling is the most representative methods for preparation of biaryl atropisomers.Alternatively,stereoselective transformations of prochiral or racemic biaryls were widely adopted.Several new methods such as construction of aromatic rings or rearomatization of substrates with chiral centers were developed in recent decades.Catellani reaction has hold great appeal since it was discovered.Aryl halides can be functionalized via such a single transformation in both ortho and ipso positions.For example,alkylation,arylation,acylation,amination,thiolation and many other transformations have been remarkably demonstrated.However,very few works on asymmetric Catellani-type reaction was reported until now.The second part shows our research on enantioselective synthesis of biaryl atropisomers via Catellani-type reaction.We chose 1-iodonaphthalene derivatives as substrates.Alkylation in the ortho position with chloromethyl benzoate followed by asymmetric cross-coupling with 2-formylphenylboronic acid derivatives furnished the biaryl atropisomers.The P,C-type ligand,which bears an axial chirality and a P center chirality,has been synthesized and shown best performance regarding both yields and enantioselectivity with high functionality tolerance.The obtained optically active atropisomers could be further converted to other functionalized axially chiral biaryls.