Substituent electronic effects in chiral ligands for asymmetric catalysis

Ferrocene-derived P,N ligands: synthesis and application in enantioselective catalysis

“…Numerous reviews have highlighted the synthesis and applications of ferrocene-based ligands in the past [12][13][14][15][16][17]. With this review, we wish to give a focused and up-to-date summary of the synthetic routes towards chiral hybrid P,N-ferrocenyl ligands and an overview of the applications of these ligands in enantioselective catalysis.…”

Synthesis of enantiomeric spirooxazolines and spirooxazolidines by the regioselective ring closure of (–)-α-pinene-based aminodiols

“…8 Further, enantiomeric oxazolines and 1,3-oxazines have proved to be extremely efficient ligands in the asymmetric catalysis of a wide range of enantioselective syntheses. 9 Chiral phosphineoxazine ligands and phosphine-oxazolidine ligands were recently successfully used in palladiumcatalyzed asymmetric allylic alkylation. In order to assess the tendencies of aminodiols 4 and 5 to furnish either a monoterpene spirooxazolidine or a monoterpene-condensed 1,3-oxazine ring, 4 and 5 were treated with phenyl, m-methoxyphenyl and ethyl isothiocyanates, which afforded the corresponding thiourea derivatives 6-11.…”

Catalytic Enantioselective Dieckmann‐Type Annulation: Synthesis of Pyrrolidines with Quaternary Stereogenic Centers

“…A striking switch to the formation of 6 a as the major (only) product was observed when the reaction was carried out at 140 8C ( [12] In the latter case, the increase in the rate of b elimination over cyclization could be attributed to the increased Lewis acidity of the rhodium(I)-diene complex relative to a rhodium(I)-bisphosphine complex. [13] We next examined the scope of this transformation with respect to the boronic acid with both 3 and the N-benzyl analogue 8 (Table 2). Higher enantioselectivities were observed with difluorphos (for 3) and synphos (for 8) than with the other enantiomerically pure ligands.…”