A marked advancement of reactivity and enantioselectivity in palladium-catalyzed asymmetric allylations was achieved by variations of electronic substituent effects in a new series of chiral P-N hybrid ligands 1. The first evident observation demonstrates that the introduction of electron-donating groups is effective to improve the catalytic performance in the allylic transformation.Palladium-mediated allylic substitutions have been widely employed as efficient and convenient tools for carboncarbon and carbon-heteroatom bond formation in the field of organic synthesis. 1 High levels of enantiocontrol and reactivity toward various types of allylic transformation and substrates has been one of major goals for which chiral ligands have been developed extensively. 2 Substituents on the ligands often play key roles electronically in various types of transition metal-catalyzed asymmetric reactions, 3 however there are only a few attentions regarding electronic substituent effects of ligands in terms of both enantioselectivity and reactivity on palladium-catalyzed asymmetric allylations. 4 We envisaged that the ligand system having a variety of substituent effects could realize practical levels of catalytic performance regarding various types of reactions and substrates. Herein, we wish to report a drastic improvement of enantioselectivity and catalytic activity by electronic substituent effects on a new series of chiral P-N hybrid ligands 1 in palladium-catalyzed asymmetric allylations.Variations on mixed-donor bidentate ligands were planned under considerations based on Hammett's rule. As mentioned in our preceding paper, 2g the strategy for preparing VALAP 5,6 was applicable to produce a variety of chiral ligands (Scheme 1). Thus chiral P-N hybrid ligands 1 7 consisting of imino groups with various phenyl substituents and the diphenylphosphino group were easily accessible by simply mixing (2S)-2-amino-1-(diphenylphosphinyl)-3-methylbutane 3 2g and the corresponding aldehydes.The catalytic performance of palladium-1 complexes was examined in asymmetric allylic substitutions of 4 by a soft anionic nucleophile derived from dimethyl malonate (reaction type 1) and methyl trimethylsilyl dimethylketene acetal (type 2) 2e as depicted in Scheme 2. Scheme 2

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A Remarkable Improvement of Catalytic Performance by Electronic Substituent Effects of Chiral P-N Hybrid Ligands in Palladium-Mediated Asymmetric Allylations. -Introduction of electron-donating substituents into the chiral Schiff base ligand (I) in the Pd-catalyzed asymmetric allylation of the ester (II) with dimethyl malonate results in a remarkable improvement of catalytic activity and enantiomeric excess.-(SAITOH,

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