Co(II)‐salen catalyzed stereoselective cyclopropanation of fluorinated styrenes

Abstract

Three cis‐selective Co(II)‐salen complexes have been developed for the asymmetric cyclopropanation of para‐fluorinated styrenes with ethyl diazoacetate. Increasing the steric reach of the C2‐symmetric ligand side chains improved the enantiomeric ratio of the reaction from 28:1 to 66:1. The methodology was exemplified by the gram‐scale synthesis of a lead compound for the treatment of castration‐resistant prostate cancer (CRPC), as well as a structurally related analog.

Nickel-Catalyzed Enantioselective Arylative Activation of Aromatic C–O Bond

“…It is noteworthy that by utilizing OH- and CH-based modifiable sites, axially chiral ArOBIN skeletons can be easily transformed into various synthetically useful intermediates, chiral ligands, and catalysts (see the Supporting Information). To further demonstrate the usage of this enantioselective cross-coupling, we conducted further derivations. For example, with potassium carbonate as the base, the methylation was accomplished by using methyl iodide in acetone and furnished compound 4 in quantitative yield with 91% ee.…”

Synthesis and characterization of Ti(IV), Zr(IV) and Al(III) salen-based complexes

“…Moreover, the incorporation of chiral centers within the salen backbone reveals an important role in enantioselective catalysis [9][10][11][12]. Most of the catalytic studies have been focused on middle and late d-block transition metal-salen complexes as catalysts for olefin epoxidation [13][14], cyclopropanation [15][16][17], aziridination [18][19][20], sulfoxidation [21][22][23], ring-opening polymerization of cyclic esters [24][25][26][27][28][29] and copolymerization of CO2 and epoxides [30][31][32]. Early transition metal complexes supported by salen ligands are relatively less reported [33][34][35][36][37].…”