Ceric(IV) Ammonium Nitrate: A Novel Reagent for the Synthesis of Homoallyl Alcohols
作者:J. S. Yadav、B. V. S. Reddy、A. D. Krishna、K. Sadasiv、Ch. Janardhana Chary
DOI:10.1246/cl.2003.248
日期:2003.3
allylation of aldehydes with allyltributylstannane using a catalytic amount of ceric ammonium nitrate in acetonitrile under mild and neutral conditions to afford the corresponding homoallyl alcohols in excellent yields with high chemoselectivity. Allylation of ketones has also been achieved with tetraallytin under similar reaction conditions.
Aldehydes undergo smooth nucleophilic addition with allyltributylstannane in the presence of CeCl3·7H2O in acetonitrile under extremely mild reaction conditions to afford the corresponding homoallylicalcohols in excellent yields with high chemoselectivity. This method is very useful especially for the allylation of aldehydes bearing acid sensitive functionalities such as TBDMS, THP ethers, acetonides
Wet silica gel promotes the chemoselective and almost complete allylation of aldehydes with 0.25–0.30 molar equivalents of tetraallyltin without an organic solvent, leaving no organotin compounds, requiring neither extraction nor chromatographic separation after the reaction, and enabling the repeated use of the silica gel.
In the photochemical reaction of allyl- and benzyltrimethylstannanes with unsymmetric α-diketones (PhCOCOR), the allylic group was introduced to the benzoyl carbon in high or excellent selectivity, whereas the acyl carbon was allylated either exclusively or predominantly under BF3-mediated reaction.
Ligand Controlled Highly Regio- and Enantioselective Synthesis of α-Acyloxyketones by Palladium-Catalyzed Allylic Alkylation of 1,2-Enediol Carbonates
作者:Barry M. Trost、Jiayi Xu、Thomas Schmidt
DOI:10.1021/ja8038954
日期:2008.9.10
The palladiumcatalyzed decarboxylative asymmetric allylic alkylation of allyl 1,2-enediol carbonates 1 can decompose to either alpha-hydroxyketones 3 or alpha-hydroxyaldehydes 4. The product distribution is largely controlled by the ligand. Using Lnaph in DME we exclusively obtained the ketone product in good to excellent yields and high enantiomeric excesses. The reaction proceeds under extremely