1.In the oxidation of 4-ethynyl-, 4-vinyl-, and 4-ethyl-decahydro-1,2-dimethyl-4-quinolinols containing an axial methyl group at C-2 with hydrogen peroxide only one isomer of the N-oxide is formed.2.In the oxidation of 4-ethynyl-, 4-vinyl-, and 4-ethyl-decahydro-1,2-dimethyl-4-quinolinole containing an equatorial methyl group at C-2 with hydrogen peroxide two isomeric N-oxides are formed.3.In the oxidation of the isomeric decahydro-1,2-dimethyl-4-vinyl-4-quinolinols with two molecular proportions of peracetic acid the main products are the corresponding 4-(epoxyethyl)decahydro-1,2-dimethyl-4-quinolinol 1-oxides.