
%0 Journal Article
%A Quinn, KJ 
%A Rae, ID 
%T Preparation of isobenzofuran-1(3H)-ones by decarbonylation of 1H-2-benzopyran-1,3(4H)-diones
%J Australian Journal of Chemistry
%D 1981/03/01
%V 34
%N 3
%P 685-690
%K 
%R https://doi.org/10.1071/CH9810685
%U https://www.publish.csiro.au/paper/CH9810685 
%X 3,3-Dimethyl-1H-2-benzopyran-1,3(4H)-dione (3,3-dimethylhomophthalic anhydride) is decarbonylated in the presence of aluminium chloride to give 3,3-dimethylisobenzofuran-l(3H)-one (3,3- dimethylphthalide) in good yield. The 5,8-difluoro anhydride reacts similarly to give the 4,7- difluoro lactone. The precursors of the anhydrides, the 3,3-dimethyl-2,3-dihydro-1H-inden-1-ones, were prepared from 3-methylbut-2-enoic acid and the appropriate aromatic compound in the presence of aluminium chloride. The difluorodihydroindenone prepared in this way is accompanied by 5,8-difluoro-4-methyl-3,4-dihydronaphthalen-1(2H)-one and a mechanism is proposed to account for its formation. 
