Reaction of cytosine with bisulfite and hydroxylamine.

The synthesis of DNA oligomer containing N(4)-hydroxy-5,6-dihydrocytosine-6-sulfonate by the simultaneous addition of bisulfite and hydroxylamine under mild conditions is reported. To the best of our knowledge, the reaction of the oxime into the ketone, N(4)-hydroxy-5,6-dihydrocytosine-6-sulfonate into 5,6-dihydrouracil-6-sulfonate or uracil has not been reported. Moreover, this issue contains the difficulty in specific reactivity of oxime derivative from DNA bases include (5m)C toward reagent; for example, T also reacts to potassium permanganate known as a reagent for oxime into ketone. Here we examined the transformation of DNA containing N(4)-hydroxy-5,6-dihydrocytosine-6-sulfonate into 5,6-dihydrouracil 6-sulfonate and the following elimination of sulfonate.