The unsymmetrically disubstituted hydrazines 1 were condensed with carbonyl compounds. Some of the expected condensation products were isolated, but some were formed as unstable intermediates which underwent 1, 4-elimination: The phenylhydrazone of the carbonyl compound used was obtained, together with the corresponding phenylazo-alkene 11 or alternatively, the 1, 4-addition product of a different protic nucleophile to 11.