Alkoxide-mediated preparation of enolates from silyl enol ethers and enol acetates - From discovery to synthetic applications

A novel route to enolates from silyl enol ethers and enol acetates has been studied and optimized. A range of lithium, sodium and, particularly, potas sium enolates were quantitatively prepared under very simple conditions. Th is new methodology involved an alkoxide-mediated reaction to form enolates, which were subjected to regiospecific alkylation, aldolisation, or Michael reaction. In some cases, only a catalytic amount of alkali metal alkoxides was needed. A new prenylation method, leading to polyene aldehydes belongi ng to the vitamin A series, has also been described. Finally, a new concept based on retroaldol reaction has been applied to asymmetric synthesis.