Ethylzinc 1,3‐bis(diphenylphosphino)‐1‐propenyl oxide, an unexpected product of the reaction between ethylzinc diphenylphosphide and β‐propiolactone

Ethylzinc diphenylphosphide effects the acyl‐oxygen ring‐opening of β‐propiolactone. However, the product of insertion into the ZnP bond spontaneously eliminates ethylzinc hydroxide with formation of acryloyldiphenylphosphine which undergoes a 1,4‐addition, not previously observed, with a second molecule of ethylzinc diphenylphosphide. The course of this unexpected reaction sequence and the structure of the final product have been elucidated by IR and NMR ( 1 H, 31 P and 13 C) spectroscopy.