Cerium chloride aldol reaction

A synthetic application of this cerium chloride methodology has been reported by Nagasawa et al., as shown in Schenne 25. It is noteworthy that aldol reaction of the cerium enolate proceeds in high yields, even though the acceptor carbonyl group is sterically crowded and is readily enolized by lithium enolates. 

Representative examples of the reactions of various carbonyl compounds with Grignard reagents under these conditions are listed in Table 5. It is emphasized that enolization, aldol reaction, ester condensation, reduction and 1,4-addition are remarkably suppressed by the use of cerium chloride. Various tertiary alcohols, which are difficult to prepare by the conventional Grignard reaction, can be synthesized by this method. 

---