title: Enhanced rate and selectivity by carboxylate salt as a basic cocatalyst in chiral N-heterocyclic carbene-catalyzed asymmetric acylation of secondary alcohols.
abstract: The rate and enantioselectivity of chiral NHC-catalyzed asymmetric acylation of alcohols with an adjacent H-bond donor functionality are remarkably enhanced in the presence of a carboxylate cocatalyst. The degree of the enhancement is correlated with the basicity of the carboxylate. With a cocatalyst and a newly developed electron-deficient chiral NHC, kinetic resolution and desymmetrization of cyclic diols and amino alcohols were achieved with extremely high selectivity (up to s = 218 and 99% ee, respectively) at a low catalyst loading (0.5 mol %). This asymmetric acylation is characterized by a unique preference for alcohols over amines, which are not converted into amides under the reaction conditions.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Kyoto 606-8501, Japan.
authors.forename: Satoru
authors.initials: S
authors.lastname: Kuwano
authors.forename: Shingo
authors.initials: S
authors.lastname: Harada
authors.forename: Bubwoong
authors.initials: B
authors.lastname: Kang
authors.forename: Raphaël
authors.initials: R
authors.lastname: Oriez
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Yamaoka
authors.forename: Kiyosei
authors.initials: K
authors.lastname: Takasu
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Yamada
mesh_terms: D000215:Acylation; D000438:Alcohols / Q000737:chemistry*; D000588:Amines / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D012492:Salts / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000438:Alcohols; D000588:Amines; D002264:Carboxylic Acids; D012492:Salts; C030011:carbene; D008697:Methane