Substituent stereochemistry effects on diastereoselective methylation reaction of 4-chloroadamantan-2-ones

π-Facial diastereoselectivity effects of the substituent in 4-position on the nucleophilic addition of substituted adamantan-2-ones were observed for the methylation reaction of 4-chloroadamantan-2-ones. NMR study revealed that when chlorine atom is in axial stereochemical position, exclusively anti-addition occurs, whereas selective preference for syn-addition was observed with stereochemical equatorial position for chloro substituent. The success of this strategy can be attributed to the important role that CeCl3 plays in increasing the nucleophilicity and decreasing the basicity of the methylorganometallic reagent.