Regio- and enantioselective Pd-catalyzed allylic alkylation of ketones through allyl enol carbonates.
The Pd-catalyzed reorganization of enol allyl carbonates to allylated ketones occurs asymmetrically in the presence of chiral ligands previously developed in this group. With 2-methylcyclohexanone, asymmetric regioselective alkylation occurs at the more substituted carbon without complications of polyalkylation. Alkylation to create quaternary centers in indanones and benzonabenone occurs in much higher ee than using tin or lithium enolates. The sense of enantioinduction in tetralones is opposite from the tin and lithium enolate examples. For the first time, asymmetric creation of tertiary centers occurs with high ee (78-99%). The different results between this reaction and the use of lithium or tin enolates suggest different mechanisms may be involved.
Trost
Barry M
BM
Department of Chemistry, Stanford University, Stanford, California 94305-5080, USA.
Xu
Jiayi
J
D000478:Alkylation; D000498:Allyl Compounds / Q000737:chemistry*; D002254:Carbonates / Q000737:chemistry*; D002384:Catalysis; D007659:Ketones / Q000138:chemical synthesis / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry; D013237:Stereoisomerism; D013379:Substrate Specificity
D000498:Allyl Compounds; D002254:Carbonates; D007659:Ketones; D010165:Palladium