A Novel Approach to Both the Enantiomers of Potent Glycosidase Inhibitor Isofagomine via PET-Promoted Cyclization of 1-[Benzyl(trimethylsilyl-methyl)amino]-1,4,5-trideoxy-2,3-O-(1-methylethylidene)-threo-pent-4-ynitol - Pandey, Ganesh; Kapur, Manmohan (Synthesis, 2001)