Allylation of Aldehydes Promoted by the CeCl3.7H2O/NaI System: the Dependence of Regio- and Stereocontrol from the Reaction Conditions

The cerium(III)chloride heptahydrate/so- dium iodide complex (CeCl3 ·7H2 O/NaI)acts as a useful promoter in the carbon-carbon bond forming reaction by addition of allyltributylstannanes to alde- hydes.The reaction of 2-butenyltributylstannane shows that the regio-and the stereochemical out- comes depend on the reaction conditions.When the promoter is adsorbed on a solid support (aluminum oxide),a highly prevalent formation of the g -adduct is observed in solvent-free conditions.Conversely, when the reaction is carried out in acetonitrile as the solvent,the a -adduct largely prevails.In the last case,a complete stereocontrol is observed,the less stable (Z )-isomer being obtained in high geometrical purity.