4-Hydroxymethylbenzisothiazolone-1,1-dioxide could be facilely synthes
ised via a highly regioselective Diels-Alder cycloaddition between fur
furyl alcohol and 2-(tert-butyl)-isothiazolone-1,1-dioxide, followed b
y aromatization of the adduct under basic conditions. A secondary effe
ct from intramolecular hydrogen bonding is found also to influence the
regioselectivity of the cycloaddition. Unequivocal proof of the regio
chemistry of the Diels-Alder reaction is provided by X-ray crystallogr
aphy and ab initio calculations showed electronic and steric effects o
n transition structure asynchronicity. (C) 1998 Elsevier Science Ltd.
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