# Grignard reagents react with epoxides but dissolve in THF, what happens in oxetane (four membered ether ring)?

Ring strain causes the epoxides to react and THF does not react because the ring strain is not large enough. Does the four membered ring react or not? Does it favor reaction with the harder or softer nucleophile perhaps - thus only reacting with some Grignard reagents?

$$\begin{array}{cccc} \ce{R} & \ce{X} & \text{Solvent} & \text{Yield (%)} \\ \hline n\text{-}\ce{C4H9} & \ce{Cl} & \text{Ether} & 75 \\ \ce{C6H5} & \ce{Br} & \text{THF} & 52 \\ \ce{CH2=CH-CH2} & \ce{Br} & \text{Ether} & 50 \\ \ce{(CH3)2C=CH-CH2} & \ce{Cl} & \text{THF} & 50 \end{array}$$