The Applications Of Novel Axial Chiral P, N Ligands TF-Biphamphos In Asymmetric Catalytic Reactions

TF-BiphamPhos were independently developed and designed as a new class of chiralphosphine nitrogen ligands by our group. CuBF4/TF-BiphamPhos catalytic system exhibitedexcellent results in asymmetric1,3-dipolar cycloaddition of various azomethine ylides withdimethyl maleate. In order to verify the efficiency and applicability of this catalytic system,we need to further broaden the dipolarophile. My research focused on the application ofTF-BiphamPhos, which were used in several catalytic asymmetric reactions. The maincontents are as followed:1. AgOAc/TF-BiphamPhos catalytic system exhibited high yields (up to99%), excellentendo-selectivities (>98:2) and enantioselectivities (up to98%ee) in asymmetric1,3-dipolarcycloaddition of azomethine ylides. And it cound also give excellent endo-products with aquaternary stereocenter at the2-position of the pyrrolidine, while maintaining excellentenantioselectivity, when used in the azomethine ylides which were especially derived from-substituted amino acids. To explain asymmetric1,3-dipolar cycloaddition reaction, apossible transition state model was proposed.2. We have successfully realized the first catalytic enantioselective1,3-dipolarcycloaddition of alkylidene malonates with azomethine ylides. The highly efficientAgOAc/TF-BiphamPhos catalytic system exhibited good yields (up to94%), excellentexo-selectivities and enantioselectivities (up to99%ee).These reactions also verified that thepossible transition state model was reasonable.3. AgOAc/TF-BiphamPhos was an efficient catalyst for the highlyenantioselective1,3-dipolar cycloaddition of azomethine ylides with cumulene4-1for theconstruction of3-vinylidene-pyrrolidine derivatives containing a unique allene moiety. Goodyields (up to92%) and excellent enantioselectivities (up to96%ee) were uniformly observedfor various azomethine ylides.4. We have successfully developed the first example of the catalytic synthesis ofenantiomerically enriched unnatural-amino acid derivatives containing gem-BPs byrealizing the direct asymmetric Michael addition of azomethine ylides with-substitutiedtetraethyl alkylidenebis (phosphonate) compounds. The highly efficientCuBF4/TF-BiphamPhos catalytic system exhibited good yields (up to95%), excellentdiastereoselectivities (syn:anti>99:1) and enantioselectivities (up to99%ee). Through aseries of experimental studies, we also confirmed that the NH2moiety of the chiralTF-BiphamPhos play a great role in this asymmetric Michael addition reaction. To elaboratethese asymmetric Michael addition reactions, a possible transition state model was proposed.