Fumiko Kato

A novel direct catalytic asymmetric synthesis of cyclic indole derivatives by intramolecular carbopalladation of allenes and subsequent intramolecular amination

Abstract A novel asymmetric synthetic method allowing a facile entry to chiral cyclic indole compounds has been developed by means of asymmetric carbopalladation–amination of allenes using a palladium catalyst with chiral phosphine ligands: intramolecular carbopalladation of allenes, which bear o -iodophenyl amino groups, was followed by intramolecular amination of the resultant π-allylpalladium intermediates. The enantioselectivity of the asymmetric reactions were found to be dependant on the chiral phosphine ligands and the solvent used; N -methylpyridone was the most effective solvent for achieving efficient enantioselectivity with high chemical yields, and ( S )-(−)-BINAP or ( S )-Tol-BINAP were revealed to be the most useful of the chiral phosphine ligands examined, depending on the substrate employed.

Stereochemical studies of the palladium-catalyzed rearrangements of chiral 2-alkynyl sulfinates into chiral allenyl sulfones

Abstract Palladium-catalyzed reactions of diastereomerically pure chiral 2-alkynyl p -toluenesulfinates under very mild reaction conditions gave both enantiomers of optically active sulfonyl allenes in good yields with high stereospecificity. The stereochemistry of this transformation with the assistance of a palladium catalyst was determined. The conversion rate was measured by the HPLC analysis in accordance with the elapse of the reaction time, and the rather marked difference of the rate was observed between the diastereomeric sulfinates. A novel mechanism for this transformation with palladium catalysts is proposed.

Stereochemistry of asymmetric cyclizations by palladium-catalyzed intramolecular asymmetric allylations of chiral enamines, imines, and hydrazones bearing phosphine groups

Abstract Chiral enamines, imines, and hydrazones bearing phosphine groups at the chiral centers and allylic parts at the appropriate positions underwent intramolecular asymmetric carbon-carbon bond formations in the palladium-catalyzed reactions to give optically active cyclized products with rather high enantiomeric excess. The mechanism for the asymmetric induction is rationalized on the basis of the stereochemical outcome observed.

Stereochemistry of transition metal catalyzed asymmetric intramolecular allyl transfer in chiral α-sulfinyl allylic esters

Abstract The stereochemistry of palladium or nickel catalyzed asymmetric intramolecular allyl transfer in chiral α-sulfinyl allylic esters was determined. The participation of the catalyst and the chiral sulfinyl functionality in these transformations, presumably by the coordination of the sulfinyl group to the catalyst, is discussed, and a novel mechanism is proposed for the rationalization of the results obtained.

Palladium-catalyzed asymmetric reactions enantiocontrolled by chiral organosulfur functionality

Abstract Participation of chiral sulfinyl functionality in palladium-catalyzed asymmetric reactions is demonstrated by using chiral sulfoxides as chiral ligands or chiral substrates. New chiral ligands, o-(phosphinoamino)phenyl and o-phosphinophenyl sulfoxides, have been developed. The structure of an intermediary palladium complex was determined by X-ray crystallographic analysis. The palladium-catalyzed asymmetric 1,3-rearrangements of (1,3-butadienyl)cyclopropanes bearing chiral sulfinyl groups to cyclopentenes are described. The participation of the chiral sulfinyl group to the palladium catalyst is described.

Asymmetric radical carboncarbon bond forming reactions in chiral amides and imides under sulfonyl groups stereocontrol

Abstract Asymmetric radical carbon–carbon bond formation was achieved in chiral amide and imide systems under sulfonyl group stereocontrol, providing high diastereoselectivity. The stereochemistry of the products was determined and the mechanism of the stereochemical pathways is rationalized by the formation of chelates of Lewis acid metals between oxygens of acetyl, amide, and imide carbonyls, or sulfonyl groups.