Organocatalytic Asymmetric Alkylation of Aldehydes by SN1-Type Reaction of Alcohols
作者:Pier Giorgio Cozzi、Fides Benfatti、Luca Zoli
DOI:10.1002/anie.200805423
日期:2009.2.2
Work‐alcoholic! The elusive enantioselective catalytic α‐alkylation of aldehydes, a widely sought transformation, was brought to execution by the use of alcohols capable of forming stabilized carbocations (see scheme, TFA=trifluoroacetic acid).
A novel coupling reaction of diaryl methanols with ketones or aldehydes has been developed under the catalysis of AlCl3. Various ketones and aldehydes could couple with 9H‐xanthen‐9‐ol smoothly, affording coupling products in 48% –88% yields. A plausible mechanism using AlCl3 to activate both diaryl methanol and ketone or aldehyde is proposed.
The acid free asymmetric intermolecular α-alkylation of aldehydes in fluorinated alcohols
作者:Jian Xiao、Kai Zhao、Teck-Peng Loh
DOI:10.1039/c2cc30261f
日期:——
The acid free asymmetric intermolecular α-alkylation of aldehydes with alcohols has been discovered using trifluoroethanol as solvent. This unprecedented system affords the enantioenriched functionalized primary alcohols (after NaBH4 reduction) in high yields and good to excellent enantioselectivities with wide substrate scope in the absence of any acid additive.