The asymmetric synthesis of the 2-O-benzyl-3,4-dideoxy-3-fluoro-[α]-D- lyxo-hexopyranose (11), the -L-ribo-, the -D-arabino-, and the -L-xylo- analogues (12 - 14) has been realized through dihydroxylation of the double bond of (5S)-5-benzyloxy-4-fluoro-6-[(R)-(4-methylphenyl)sulphinyl]-hex-1-ene (4) followed by oxidative removal of the chiral auxiliary sulphinyl group. A detailed spectroscopic analysis
from (2R,3S)-2-benzyloxy-3-fluoro-5-hexenale 2 and its (2R,3R) epimer, cyclopentanoisoxazolidines 4 and 7 are obtained with complete diastereoselectivity through nitrone and oxime intiainolecular cycloaddition reactions. In contrast, cyclopentanoisoxazolines 6 are formed with only medium stereoselectivily through intramolecularnitrileoxidecycloaddition reactions. Further elaboration of these bicyclic