METHYL 2-AZIDO-3-O-BENZYL-2-DEOXY-ALPHA-D-MANNOFURANOSIDE AS A DIVERGENT INTERMEDIATE FOR THE SYNTHESIS OF POLYHYDROXYLATED PIPERIDINES AND PYRROLIDINES - SYNTHESIS OF 2,5-DIDEOXY-2,5-IMINO-D-MANNITOL [2R,5R-DIHYDROXYMETHYL-3R,4R-DIHYDROXYPYRROLIDINE]