A new stabilised form of isobenzofuran, rack-mounted on an alicyclophane

<p dir="ltr">New stable, crystalline isobenzofurans <b>9a</b> and <b>9b</b> linked through the 1,3-positions and incorporated into alicyclophanes have been prepared from the related furano-alicyclophane <b>5</b> in three steps (i) addition of benzyne or 4,5-bis(trimethylsilyl)benzyne (ii) hydrogenation of the π-bond (iii) ejection of ethylene by flash vacuum pyrolysis, and shown to yet retain high 1,3-diene character and form adducts with dienophiles, <i>e.g.</i> dimethyl acetylenedicarboxylate or <i>N</i>-methyl maleimide; the corresponding off-rack 1,3-dimethylisobenzofurans were too unstable for isolation.</p>