Geometry‐Directed Generation and Synthetic Application of α‐Lithio Oxime Ethers

Several mono‐ and di‐O‐alkyloximes have been regioselectively transformed to the syn α‐lithio derivatives by treatment with n‐butyllithium. The control of oxime ether geometry served to control regioselectivity in α‐lithiation and subsequent carbon‐carbon (alkylation, oxidative coupling) and carbon‐halogen bond formation reactions. The geometry‐directed α‐lithiation‐dimerization sequence was used for the synthesis of large ring compounds.