Reactions between some organozinc compounds and 2-dimethylaminoethanol, acetoxime, phenylisocyanate, and benzophenone. Some observations on the methylzinc methoxide tetramer
Zinc alkyls and 2-dimethylaminoethanol eliminate hydrocarbon giving trimers (RZnO·C2H4·NMe2)3(R = Me, Et). The tetrameric products, e.g., (MeZnON:CMe2)4 and (EtZnNPhCOEt)4, from zinc alkyls and acetoxime and phenyl isocyanate are formulated with parallel six- and eight-membered rings, respectively, the interaction between the rings arising from the tendency of the metal to be four rather than three co-ordinate.
The near-cubic structure of the crystalline methylzinc methoxide tetramer persists in cyclohexane solution and interaction with pyridine is slight. · The tetramer yields an adduct with 4-dimethylaminopyridine which dissociates extensively in solution to tetramer and free base.
Diethylzinc eliminates ethylene quantitatively in reaction with benzophenone, giving the trimer (EtZnOCHPh2)3. Diphenylzinc adds to the carbonyl group forming a dimer, (PhZnOCPh3)2.