METAL SALT-PROMOTED ALDOL REACTION OF SILYL ENOL ETHERS WITH ALDEHYDES

Simple metal salts such as lithium perchlorate and zinc triflate effec tively promote aldol condensation between silyl enol ethers and aldehy des or acetals in non-protic solvents to yield the O-protected aldols in good yields. A slight preference for the syn aldol is observed when a prochiral silyl enol ether reacts with benzaldehyde, a complete syn stereoselectivity being obtained only in the case of the hindered sil yl enol ether 14. The method appears to be simple and competitive with other ones previously described.