Zhao-Lin He

A Facile Access to Enantioenriched Isoindolines via One-Pot Sequential Cu(I)-Catalyzed Asymmetric 1,3-Dipolar Cycloaddition/Aromatization

Facile access to enantioenriched isoindolines bearing a quaternary stereogenic center and a tertiary stereogenic center was successfully developed via highly efficient Cu(I)/(S,Rp)-PPFOMe-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylide with quinone derivatives followed by silica-gel-promoted oxidation [corrected] in a one-pot reaction protocol. The present catalytic system exhibited high diastereoselectivity, excellent enantioselectivity, and a broad substrate scope under mild conditions.

Stereoselective Construction of Spiro(butyrolactonepyrrolidines) by Highly Efficient Copper(I)/TF‐BiphamPhos‐Catalyzed Asymmetric 1,3‐Dipolar Cycloaddition

Pyrrole into one: The catalytic asymmetric 1,3-dipolar cycloaddition of cyclic aldimino esters has been accomplished for the first time, enabling facile access to spiro(butyrolactonepyrrolidines) containing one spiro quaternary center and three tertiary stereogenic centers (see scheme). The catalytic system performs well with a broad range of substrates, furnishing synthetically useful adducts in high yields, with excellent diastereo- and enantioselectivities under mild conditions.

Silver(I)-Catalyzed Enantioselective Desymmetrization of Cyclopentenediones: Access to Highly Functionalized Bicyclic Pyrrolidines

A highly enantioselective desymmetrization of prochiral cyclopentenediones via Ag(I)-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylide has been developed successfully. The methodology performs well over a broad scope of substrates, which provides facile access to a series of highly functionalized bicyclic pyrrolidine/cyclopentane derivatives in good to high yields with excellent stereoselectivities.

Exoselective 1,3-dipolar [3 + 6] cycloaddition of azomethine ylides with 2-acylcycloheptatrienes: stereoselectivity and mechanistic insight.

A highly exo-selective 1,3-dipolar [3 + 6] cycloaddition of azomethine ylides with 2-acylcycloheptatrienes was realized with a Cu(I)/(S,R(p))-PPF-NHMe complex as the catalyst, leading to a diverse range of bridged piperidines with multiple functionalities in good yield with excellent stereoselectivity control. Theoretical calculations indicated a stepwise mechanism for this exo-selective [3 + 6] annulation, which accounts for the remarkable feature of this annulation: all of the larger substituent groups occupy the axial positions in the six-membered chairlike conformation of the piperidine ring.

Catalytic asymmetric construction of spiro pyrrolidines with contiguous quaternary centers via 1,3-dipolar cycloaddition of azomethine ylides

Bioactive 5-aza-spiro[2,4]heptanes with high functionality and up to three contiguous all-carbon quaternary stereogenic centers were synthesized by Cu(I)-catalyzed asymmetric endo-selective 1,3-dipolar cycloaddition of azomethine ylides with cyclopropylidene acetates. This synthesis system performs well for a broad scope of substrates. α-unsubstituted/α-substituted azomethine ylides and cyclopropylidene acetates are compatible 1,3-dipoles and dipolarophiles, which afford the spiro heterocycles with contiguous quaternary centers at 2-, 3- and 4-positions of the pyrrolidine ring in good yield (up to 97%) and high diastereoselectivity (95:5–>98:2 d.r) and excellent enantioselectivity (87%–98% ee).

Cu(I)/TF–BiphamPhos-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides with dimethyl itaconate and 2-methyleneglutarate

Catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides with dimethyl itaconate and 2-methyleneglutarate was realized with the Cu(I)/TF–BiphamPhos complex as the catalyst for the efficient construction of pyrrolidine derivatives bearing one unique all carbon-quaternary and two tertiary stereogenic centers. The current catalytic system exhibited excellent diastereoselectivity (> 20:1), good enantioselectivity (88–>99% ee) and broad substrate scope under mild conditions.