Nomenclature of acid anhydride I have been struggling hard for writing IUPAC naming of this compound. 



Anhydride with benzene having five membered ring can be named as benzene dicarboxylic anhydride and five membered ring without benzene can be named as pentane -1,5-dioic anhydride. But what can I do for this compound?
It looks like a isochroman-1,3-dione to me.

For the reference there is a similar compound (published in French): Kakou-Yao, R.; Saba, A.; Ebby, N.; Pierrot, M.; Aycard, J. P. Tautomérie de la 4-(hydroxyphénylméthylène) isochroman-1,3 dione à l'état solide, Acta Cryst C 1999, 55 (9), 1591–1593. DOI: 10.1107/S0108270199006782