Synthesis and Antibacterial Activity of New 3-Benzylspiro[benzo[h]quinazoline-5,1′-cycloheptan]-4(6H)-one Derivatives

The condensation of 3-benzyl-2-sulfanylidene-2,3-dihydro-1H-spiro[benzo[h]quinazoline-5,1′-cyclo­heptan]-4(6H)-one with 5,5-dialkyl-2-(chloromethyl)benzo[h]quinazolines gave bis-benzo[h]quinazoline compounds in which the spiro[benzo[h]quinazoline-5,1′-cycloheptane] fragment is linked through the 2-position to another benzo[h]quinazoline moiety via a SCH₂ spacer. 3-Benzyl-2-sulfanylidene-2,3-dihydro-1H-spiro­[benzo[h]quinazoline-5,1′-cycloheptan]-4(6H)-one reacted under similar conditions with methylene iodide to produce 2,2′-[methylenebis(sulfanediyl)]bis{3-benzyl-3H-spiro[benzo[h]quinazoline-5,1′-cycloheptan]-4(6H)-one}. The initial benzo[h]quinazoline was converted to 2-hydrazinyl derivative which underwent elimination of the hydrazine moiety by the action of alkali with the formation of 3-benzyl-3H-spiro[benzo[h]quinazoline-5,1′-cycloheptan]-4(6H)-one. The 2-hydrazinyl derivative was used to obtain the corresponding phenylhydrazone, thiosemicarbazide, and 4-benzyl-4H-spiro[benzo[h][1,2,4]triazolo[4,3-a]quinazoline-6,1′-cycloheptanone]-5(7H)-one. The alkylation of 4-benzyl-1-sulfanyl-4H-spiro[benzo[h][1,2,4]triazolo[4,3-a]quinazoline-6,1′-cycloheptan]-5(7H)-one with alkyl halides afforded the corresponding 1-alkylsulfanyl derivatives. The synthe­sized compounds were tested for antibacterial activity.