The unexpected formation of a lithium enolate from bis-{2-[(dimethylamino) methyl]phenyl}coppers lithium. X-ray structure of Li4[OC(=CH2)C6H4CH2NMe2-2]4

Abstract

Attempted crystallization of the bis(aryl)lithium cuprate, Cu{2}Li{2}(C{6}H{4}CH{2}-NMe{2}-2){4}, from diethyl ether/pentane afforded in according to an X-ray diffraction analysis appeared to be the lithium enolate, Li{4}[OC(=CH{2})C{6}H{4}CH{2}NMe{2}-2]{4}. This consists of a central Li{4}O{4} cube with intramolecular Li@?N coordination of the CH{2}NMe{2} substituent. This enolate, which has also been prepared via an independent route, is the first example of a structurally characterized lithium enolate and contains Li centres that are intramolecularly coordinated.