NOVELTY - Preparing (P1) methyl 5-acetamido-4-amino-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate involves reducing methyl 5-acetamido-4-azido-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate in the presence of a reducing agent selected from lithium aluminum hydride, sodium borohydride, zinc/ammonium chloride, zinc-ferric chloride and ferric chloride/sodium iodide.    USE - For preparation of methyl 5-acetamido-4-amino-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate, which are intermediates for the synthesis of zanamivir (all claimed) used in the treatment and prophylaxis of both Influenza virus A and Influenza virus B.    ADVANTAGE - The process involves the use of zinc/ammonium chloride as the reducing agent which is a cheap and easily recoverable catalyst. With the use of this catalyst, the time required for completion of reaction is shorter as compared to the prior art processes, where about 4-16 hours are required for reduction to take place. The use of zinc does not cause undesired reduction of the 2,3-double bond of the ring thus preventing formation of side-products. The process is simple, economical, eco-friendly and industrially scaleable.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) new intermediates methyl 5-acetamido-4-cyanamido-6-(1,2,3-triacetoxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate (VIII) and methyl 5-acetamido-4-cyanamido-6-(1,2,3-trihydroxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate (IX);    (2) preparation of the compound (VIII) and (IX);    (3) preparing (P2) (4S,5R,6R)-5-acetylamino-4-cyanoamino-6-((1R,2R)-1,2,3-trihydroxy-propyl)-5,6-dihydro-4H-pyran-2-carboxylic acid (VII) involving hydrolyzing methyl 5-acetamido-4-cyanamido-6-(1,2,3-trihydroxypropyl)-5,6-dihydro-4H-pyran-2-carboxylate (IX);    (4) preparing (P3) zanamivir involving preparing the compound (VII), and reacting the compound (VII) with ammonium formate in the presence of ammonia to obtain zanamivir; and    (5) zanamivir having purity greater than or equal to 99.5%.