Ag/P-Stereogenic Phosphine-Catalyzed Enantioselective 1,3-Dipolar Cycloadditions: A Method to Optically Active Pyrrolidines

Abstract

A Ag/P-stereogenic phosphine-complex-catalyzed 1,3-dipolar cycloaddition of azomethine ylides with electrondeficient olefins is reported. In this reaction, highly functionalized pyrrolines with a spiro-quaternary stereogenic center were obtained in good yields (up to 99%) with excellent levels of diastereo-(up to >20:1 dr) and enantioselectivities (up to >99% ee). The chirality of adducts was controlled predominantly by the P-stereogenic phosphines.

Review on asymmetric cycloaddition reactions at phosphorus (III) atom

“…Related 1-phosphanorbornenes have shown excellent results in asymmetric transition metal catalysis and organocatalysis (ee values are of 90-99%). [35][36][37][38][39][40] The use of such rigid polycyclic phosphines provides fixed P-chirality by a non-racemizable chiral phosphorus center, whose geometry precludes any loss of enantiomeric purity during catalysis or the associated recycling processes. [41][42][43]…”

The Crucial Role of S‐oxidation State on the Selectivity and Reaction Rate of the 1,3‐Dipolar Cycloaddition of Azomethine Ylides and Homochiral Thiazolines

“…[1,2] A vast number of publications have been published since several years ago dealing with the insights of this cycloaddition due to the versatile organic molecules obtained through this methodology. [3][4][5][6][7][8][9][10][11][12] More interesting is the asymmetric version of this reaction, which allows to obtain up to 4 stereogenic centers in one reaction step in a selective manner, classically achieved by the use of metal-or organocatalysis. [13][14][15][16][17][18][19][20][21] The origin of the exo/endo selectivity in the catalytic asymmetric synthesis of pyrrolidines by 1,3-dipolar cycloaddition of azomethine ylides has been brilliantly rationalized and reported recently.…”

Rigid P-Chiral Phosphorus Ligands for Highly Selective Palladium-Catalyzed (4+2) and (4+4) Annulations

“…The chiral oxazoline motif was thus more flexible. Advancing from the previous compounds Ganphos and Jiaphos, they could be modularly accessed with ease and conveniently derivatized in a scalable manner. The shackled P atom could directly afford an easily established P chiral center but prevented the synthetic steps from chiral resolution.…”