Spiro-sulfamidate and sulfate nucleosides via 2′ and 3′-C-branched-chain sugars and nucleosides

C-branched-chain sugars and nucleosides were obtained by organocatalysis from ulose derivatives. After a reduction step, the corresponding 1,3-diol was derivatized into 3′-spiro-sulfamidates and unexpected sulfates by treatment with a Burgess reagent. Deprotection of the Boc-derivatives was carried out while preserving the cyclic sulfate. An example of ring opening of the cyclic sulfate derivative with sodium azide leading to the corresponding 3′-C-azidoalkyl branched-chain nucleosides is given.