ADDITION OF STANNYLATED CARBOXYLIC ACID DERIVATIVES TO THE CARBONYL GROUP OF ALDEHYDES

Article abstract of DOI:10.1016/0022-328X(85)87335-6

Addition reactions of Bu3SnCH2COOEt with PhCHO at 75 deg C in the presence of Bu3SnI and reactions of Et3SnCH2X (X=COOEt, CN, CONMe2) with benzaldehyde, cynnamaldehyde and furfural at 20 deg C in DMSO in the presence of Me4NF (2 mol percent) were investigated.Adducts obtained in high yield in these reactions readily undergo hydrolysis (when treated with aqueous KF) and acetolysis (when treated with AcCl) with quantitative formation of 3-hydroxy and 3-acetoxy derivatives of esters, nitriles and amides.We show that interaction of Et3SnCH2COOEt with the above-mentioned aldehydes and isovaleraldehyde in the presence of equimolar amounts of Et4NCl in CH2Cl2/HMPTA (10/1) at 20 deg C followed by treatment of the reaction mixture with AcCl readily gives 3-acetoxyesters.Reactions of PhCH(SnMe3)COOEt with acrolein, crotonaldehyde and cinnamaldehyde and the hydrolysis of the obtained adducts lead exclusively to 1,2-addition products, these reactions are virtually non-stereoselective.The reaction of PhCH(SnMe3)COOEt with benzaldehyde at 20 deg C in DMF, CH2Cl2 or without solvent gives mainly threo-ethyl(2,3-diphenyl-3-hydroxy)propoinate whereas at -78 deg C in CH2Cl2 in the presence of BF3*Et2O erythro isomer is mainly formed.The data obtained are discussed within the framework of the mechanism involving the participation of the O-isomer CH2=C(OEt)OSnR3.This active intermediate is formed via metallotropic rearrangement of the starting organotin compound.