Pfaltz ligand system

S. P. Smidt, F. Menges, A. Pfaltz, SimplePHOX, a readily available chiral ligand system for iridium-catalyzed asymmetric hydrogenation, Org. Lett. 2004, 6, 2023. 

Pfaltz and coworkers [29] had previously investigated the allylic alkylation of l,3-diphenylprop-2-enyl acetate with dimethyl malonate as nucleophile (in the presence of A/ ,0-bis(trimethylsilyl)acetamide, BSA) with the well-established BOX ligands as stereodirecting ligands, and this particular system therefore provided the point of reference for the catalytic study at hand (Table 15.3, entry 1) [28]. Under the reaction conditions displayed in Scheme 15.4, the trisoxazoline-based catalysts generally induce a better enantioselectivity compared to their BOX analogs, and this behavior appears to be independent of the substituent, as shown in Table 15.3. 

---