AbstractA novel reaction between ethyl allenoate and oxindoles that enables the asymmetric synthesis of 3,3‐bisubstituted oxindoles with our previously established bifunctional N‐acyl aminophosphine catalysts is reported. These products bearing a chiral quaternary carbon center at the C‐3 position of the oxindoles may have potential significance in the synthesis of related structures. The best performance of these processes provides adducts with 92% yield and 94% ee.magnified image
A range of 3,3-disubstituted oxindoles accessed using para-quinone methides derived from isatins with thiols were used for the formation of unsymmetrical disulfides, and 3,3-disubstituted oxindoles with a chiral quaternary carbon center and unsymmetric disulfides could also be directly obtained with high selectivities catalyzed by chiral phosphines in one step.
The Palladium-catalyzed Asymmetric Allylations of Chiral Hydrazones Bearing Phosphine Groups. Stereoelectronic Effects of Allylating Reagents on Asymmetric Induction
palladium-catalyzed allylations of chiralhydrazones bearing phosphine groups were executed successfully under neutral reaction conditions with various allylating reagents, affording optically active α-allyl carbonyl compounds. The systematic and stereochemical investigation of these reactions shows that the intramolecularly-substituted phosphine groups served as chiral ligands and the anionic counterparts
Bifunctional catalyst: Simple bifunctional N‐Acyl aminophosphines such as 1 were developed to catalyze the first asymmetric [3+2] cycloaddition between allenoates and dual activated olefins. The cycloaddition reactions afford multifunctional chiral cyclopentenes with exclusive regioselectivity, and good to excellent enantioselectivity and yields.
Several thioaryl- and phosphino-phosphoramidite ligands have been synthesized from commercially available beta-aminoalcohols. This new family of bidentate ligands are highly active in the enantioselective copper-catalyzed conjugate addition of diethylzinc to both cyclic and acyclic enones showing moderate to good enantiomeric excesses of up to 81%. (c) 2006 Elsevier Ltd. All rights reserved.