There is a question in my textbook asking for the reaction conditions required to convert methyl propanoate to 4-ethyl-4-heptanol. The answer key states that using propylmagnesium bromide in ethoxide with acid workup will yield the desired product. However, this does not make sense to me. Where is the extra carbon coming from on the carbonyl side of the molecule and why is there an ethyl group where the carbonyl was and not a propyl?