4H-dinaphtho[2,1-f:1', 2'-h][1,5]dithionin-S,S'-tetroxide: Preparation, structure elucidation and facile intramolecular [2+2]-photocyclization

The preparation of compound 1, a conformational study in solution and the unexpectedly facile rearrangement into 2 via photochemical intramolecular [2+2]-cycloaddition is described: The structure of these compounds have been investigated by NMR and X-ray diffraction.