In our search for new types of antidepressants, we had occasion to synthesize the title compound (3a), which, on the basis of tests with animals, seems to possess potent antidepressant-like properties. The biological data on 3a, and its N-methyl derivative (3b), are listed in Table I along with those of amitriptyline and imipramine, two tricyclic antidepressants in clinical practice. As is evident from the table, 3a is thrice as potent in mice and several times as potent in rats as amitriptyline and imipramine in reversing the ptosis induced by tetrabenazine (TBZ) in these species. It exhibits neither stimulation nor dose-induced depression in mice and rats and is not a monoamine oxidase inhibitor in vitro or in vivo. The outstanding feature of its profile is that it lacks both peripheral and central anticholinergic activity as borne out by the oxotremorine antagonism test in mice in which it is inactive in contrast to both amitriptyline and imipramine. In a 12-day subacute toxicity study with rats, 3a was well tolerated up to a dose of 50 mg/kg PO, which represents 100 times the ED50 value. The N-methyl derivative (3b) of 3a, while equipotent to amitriptyline and imipramine in mice, is however less active than 3a. Besides, it is fairly potent in the oxotremorine antagonism test indicative of undesirable anticholinergic side effects and is, therefore, less interesting than 3a. Compound 3a was synthesized by the Diels-Alder reaction of anthracene with 1-(ethoxycarbonyl)-1,2,3,6-tetrahydropyridine (1) to yield 2, the best condition for which was the use of a large excess of 1 as the solvent and heating the mixture at reflux for 18 h under nitrogen. Removal of the excess of 1 under reduced pressure furnished, in an almost quantitative yield, 2, which, on hydrolysis with KOH in boiling t-butyl alcohol with concomitant loss of CO2, afforded 3 (R = H) as a colorless crystalline solid (mp 161-162 °C, from hexane). It was converted to its hydrochloride 3a (mp 339-340 °C dec, from methanol) for screening purposes. Reduction of 2 with lithium aluminum hydride yielded 3 (R = CH3), which was isolated as its hydrochloride, 3b (mp 173-175 °C, from THF). The structures of 3a and 3b were confirmed by elemental analysis and by the NMR and mass spectra of the corresponding bases. At the time the compounds 3a and 3b were synthesized, the parent heterocyclic ring system was unknown. The synthesis of 4, a dehydro derivative of 3 (R = H), has recently been described and follows an entirely different route. No biological activity has been reported on this compound (4). Compounds 3a and 3b seem to elicit their antidepressant activity by inhibiting the reuptake of norepinephrine into terminal neuronal granules as the tricyclic antidepressants, amitriptyline and imipramine, do. This was demonstrated by the test involving 3H-NE uptake by the rat heart widely employed in the evaluation of antidepressants in which 3a was more, and 3b less, active than imipramine. At the same time it was established that they do not cause release of norepinephrine. Also, in the amine pressor response study in the dogs, another test used to characterize antidepressants, 3a was more potent than amitriptyline and imipramine in potentiating the effect of norepinephrine and about as potent as the latter in antagonizing the effect of phenethylamine. Compound 3a thus seems to be a potential potent antidepressant possessing an unusual structure; 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 ferric chloride. 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 2,5-dihydro-1-hydroxy-2-(p-tolylsulfonyl)-1H-2,1-benzazaborole (3) and 1-hydroxy-1,2,3,4-tetrahydro-2-(p-tolylsulfonyl)-2,1-benzazaborine (4) as well as the carbacyclic benzodiazaborine analogue 4-hydroxy-3-(p-tolylsulfonyl)isoquinoline (7). The nature of the active species is briefly discussed.