Classical One Step Syntheses of Mono - and Di - Nitrate Sugars via Triflates

The nitrate esters of carbohydrates, in particular of polysaccharides, have long been of considerable, importance as explosives [1]. In recent years, there has been much interest also in the nitrate esters of simpler sugars which have been found to be useful intermediates in synthetic carbohydrate chemistry [2]. The chief chemical use of such nitrates has arisen from oppurtunities to take advantage of their stabili­ ty, the easy, selective removal of the nitrate groups from certain positions, and their ready and complete denitration by reductive processes. In addition to their synthetic importance, certain sugar nitrates have biologically, significant properties [2], To data, most of the syntheses of sugar nitrates have relied upon the esterification of free hydroxyl groups with a variety of nitrating reagents [2]. These not only lack selectivity in presence of acid-labile groups but also require close control of time and temperature. Some sugar nitrates have also been synthesized through displacement of halides with silver nitrate [3] but the method has limited applica­ bility due to competing elimination reactions, molecular rearrangements, and inability to effect dis­ placement in certain positions, particularly when the leaving group is attached to a secondary carbon. A reaction which overcomes many to these limiting fac­ tors is the Sn-2 displacement of the triflyl group with tetrabutylammonium nitrate. The effectiveness of