# Reaction mechanism of a terminal alkene with an anhydride

In a reaction (as given in my textbook),

$$\ce{R-CH=CH2 + (CH3-CO)2O -> R-CH2=CH-COCH3}$$

an alkene reacts with acetic anhydride to give methyl alkenyl ketone.

I am not sure of how this proceeds, a search on google displays no links to any relevant matter, and I have not successfully found this reaction in any of the other books I possess.

According to me, it should have been an addition reaction (characteristic of alkenes) across the double bond. But this isn't the case here. So, what exactly is the reaction mechanism?