Synergic Sedation of Sensitive Anions: Alkali-Mediated Zincation of Cyclic Ethers and Ethene

Zinc-Based Bases Conventional methods of stripping a proton from a hydrocarbon yield an alkali metal-coordinated carbanion as the preliminary product. In certain cases, however, this preliminary product falls apart before it can be used for further constructive synthetic purposes. Kennedy et al. (p. 706 ; see the Perspective by Marek ) show that in such cases, zinc ions can act as potent stabilizers. Specifically, a bimetallic base incorporating both sodium and zinc ions was used to deprotonate the common cyclic ethers tetrahydrofuran and tetrahydropyran. Zinc coordination to the carbanion inhibited an otherwise rapid ring-opening decomposition pathway. Similarly, a zinc-potassium combination facilitated deprotonation of ethylene to a stabilized product.