Abstract Hydroxylamine-and hydrazine-induced heterocyclization of readily available 5- hydroxy-2.4-diacetyl-5-methyl-3R-cyclohexanones (R= methyl, phenyl, m-nitrophenyl, α- furyl) yielded 6-acetyl-5-hydroxy-5.9-dimethyl-7R-1-aza (oxa)-2-azabicyclo [4.3. 0]-2, 8- nonadienes (R= methyl, phenyl, m-nitrophenyl. α-furyl). The biological activity of the latter was tested using the Escherichia coli phage T 4, and was also tested on a stored ...