4 trans-1 (Ar= p-CH3C6H4) in this system. In the initial Diels-Alder reaction trans-1 proved far more reactive than the corresponding cis isomer2 and was therefore used exclusively in this study. Not wishing to be faced, in expectation of eventual large-scale work, with the tedious handling of massive quantities of toxic metallic mercury, we devised a simple method of desulfonylation involving treatment of the appropriate bis (su1fone) with an ...