A novel and general alpha-regioselective and highly enantioselective prenylation of aldehydes.
This communication describes a novel and general method for the alpha-regioselective prenylation of carbonyl compounds. This method which employs chiral gamma-prenyl-1,5 diol as the prenyl source using a catalytic amount of Lewis or Brønsted acid affords the products in excellent enantioselectivies (up to 98% ee) and good yields (up to 95% yield). Furthermore, the reaction is highly chemoselective, reacting selectively with the aldehyde without affecting the enone and the alpha,beta-unsaturated ester functionalities. Detailed mechanistic studies disclose the facile epimerization of aromatic alcohol in dichloromethane in the presence of In(OTf)3. The use of non-polar solvents such as hexane in the presence of In(OTf)3 or TfOH effectively suppresses this epimerization.
Cheng
Hin-Soon
HS
Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543.
Loh
Teck-Peng
TP
D000438:Alcohols / Q000138:chemical synthesis*; D000447:Aldehydes / Q000737:chemistry*; D017368:Protein Prenylation; D013237:Stereoisomerism
D000438:Alcohols; D000447:Aldehydes