
%0 Journal Article
%A Russell, RA 
%A Marsden, DE 
%A Sterns, M 
%A Warrener, RN 
%T Preparation and trapping of 1-Acetoxyisobenzofuran. The structure of a novel phthalide formed in the attempted generation of 1-Acetoxyisobenzofuran in the presence of quinones
%J Australian Journal of Chemistry
%D 1981/06/01
%V 34
%N 6
%P 1223-1234
%K 
%R https://doi.org/10.1071/CH9811223
%U https://www.publish.csiro.au/paper/CH9811223 
%X A new potential synthesis of anthraquinones based upon 1-acetoxyisobenzofuran (4) is reported. The key reaction used to generate isobenzofurans, namely the s-tetrazine reaction, proceeds smoothly in the presence of N-methylmaleimide to yield the expected adduct (16). In contrast, the reaction takes a different path in the presence of quinones to yield a novel phthalide (15). These reactions are considered to involve a non-concerted fragmentation of the intermediate dihydro-pyridazine (3) to yield the stabilized zwitterionic species (13). The zwitterion leads on to the phthalide (15) in a two step sequence involving the quinone as oxidant, while normal fragmentation is the sole reaction in the absence of oxidant.     The structure of 3-[3',6'-di(pyridin-2''-yl)pyridazin-4'- yl]isobenzofuran-1(3H)-one (15) has been determined by single crystal X-ray diffraction and refined by full-matrix least squares to a residual of 0.107 for 1389 'observed' reflections. Crystals are monoclinic, P21/c, a 8.271(2), b 19.183(4), c 11.814(2)&#506;, &#946; 110.0(1)&#946;. 
