In order to develop new theories for desensitization, a potential skin sensitizer, 1, with two different haptenic ends,(a) a pyrocatechol group and (b) an a-methylene-y-butyrolactone moiety, separated by a straight nine-carbon-atom chain has been prepared and used to sensitize guinea pigs. A “monohapten” 8 containing an electrophylic a-methylene-y- butyrolactone, connected to a dimethoxybenzene group, has also been prepared. Both ...