1,2-Dihydro-1-hydroxy-2-(organosulfonyl)areno[d][1,2,3]diazaborines 2 (arene = benzene, naphthalene, thiophene, furan, pyrrole) were synthesized by reaction of (organosulfonyl)hydrazones of arene aldehydes or ketones with tribromoborane in the presence of FeCl3. The activities of 2 against bacteria in vitro and in vivo (Escherichia coli) were determined and structure-activity relationships are discussed. Included in this study are 2,3-dihydro-1-hydroxy-2-(p-tolylsulfonyl)-1H-2,1-benzazaborole and 1-hydroxy-1,2,3,4-tetrahydro-2-(p-tolylsulfonyl)-2,1-benzazaborine, as well as the carbacyclic benzodiazaborine analog 4-hydroxy-3-(p-tolylsulfonyl)isoquinoline. The nature of the active species is briefly discussed.