Cleavage of the C-S bond of predominantly with carbon-oxygen dibenzothiophene 5,5-dioxide (1) by alkoxide ions proceeds bond formation, in contrast to the observation of predominant __ _ sulfur-oxygen bond formation in the reaction of 1 with hydroxide. The esr spectrum of the radical anion of 1 has been observed in the reacting system. We recently reported that the reaction of dibenzothiophene 5,5-dioxide, 1, with KOH yields 20-30% of Z-~Z'-hydroxyphenyl)benzenesulfinic acid, Za, as well as P-benzenesulfonic acid, 3, and 2-phenylphenol, 4.l Previous workers report 3 as the only sulfur-containing product2s3. m-@SK+ @Jg+ & (l) 1 2a, R = K 3 4 2b, R = CH 3 2c, R = (CH3)3C In an attempt to delineate the generality of the competition between pathways leading to products such as 2 and 3, we have studied reactions of 1 with other strong bases and report the results for alkoxides here. In contrast to the reaction of 1 with hydroxide in which 3 predominates, reaction of 1 with alkoxides affords 2'-substituted 2-phenylbenzenesulfinic acid derivatives 2 as the main products: the 2'-methoxy derivative 2b from methoxide or the dianion of 2-(2'-hydroxyphenyl)benzenesulfinic acid, 2a, from t-butoxide (see Table 1). The detection of small amounts of 2c in the t-butoxide reaction and the known propensity of t-butyl aryl ethers to undergo elimination reactions in the presence of strong base4, reaction. Two mechanisms addition faryne) pathway, suggests that alkyl aryl ethers 2b or 2c are the initial products of the for conversion of 1 into 2 come immediately to mind: (1) an eliminationequation 2, and (2) an addition-elimination (SNAr) pathway, equation 3.