Distinct chemoselectivity in the reaction of N-(thio)phosphoryl imines with diethylzinc

Several types of (thio)phosphonylimines were synthesized and their reaction with diethylzinc was investigated in detail. An interesting and distinct chemoselectivity between hydrogen-addition and ethyl-addition to imine double bond is disclosed. The corresponding reduction product was obtained in excellent yield in nonpolar solvent toluene. However, the corresponding ethylation product was obtained exclusively in the presence of strongly coordinative additive N,N,N′,N′-tetramethylethylenediamine (TMEDA).