Dialkyl Ethers and Sacrificial Zinc: Oxide Synthons for Calcium tert ‐Butoxide Formation

ABSTRACT The calcium hydride, [(BDI)CaH] 2 (BDI = HC{C(Me)NDipp} 2 , where Dipp = 2,6‐ i‐ Pr 2 C 6 H 3 ), reacts with Zn t ‐Bu 2 to form the monomeric and toluene‐stabilised calcium dialkyl(hydrido)zincate, [(BDI)Ca‐μ‐H‐Zn( t ‐Bu) 2 (η 6 ‐C 7 H 8 )]. When treated with dialkyl ethers, this compound initiates a sequence of twofold ether deprotonation and dealkylation by alkene extrusion, from which the resultant oxide dianion is sequestered as a tert ‐butoxide anion. Through a combination of experiment and theory, this completely selective C─O bond forming process is deduced to result from the formation of incipient calcium tert ‐butyl and hydride intermediates, and subsequent tertiary carbenium ion generation enabled by reduction of Zn(II) to elemental zinc. The overall transformation, therefore, may be rationalised as a consequence of latent extreme basicity in harness with a cooperative redox process that is intrinsic to the combination of dissimilar constituent metals.