The intramolecular nitrone cycloaddition of three sets of 3-O-allylpyranose and the corresponding homochiral 3-O-allylfuranose-5-aldehyde derivatives was studied; one set derived from D-allose gave rise to only pyran derivatives which were converted to enantiomeric pyranoisoxazolidines via minor degradations.
Synthesis of chiral oxepanes and pyrans by 3-O-allylcarbohydrate nitrone cycloaddition (3-OACNC)
3-O-Allylcarbohydrate nitronecycloaddition (3-OACNC) furnished pyran and oxepane derivatives from 3-O-allyl hexose N-benzyl nitrones and 3-O-allyl furanoside-5-aldehyde N-benzyl/methyl nitrones. The regioselectivity of 3-OACNC was found to depend on the following factors (a) the structural nature of the nitrone (b) substitution and stereochemistry at 3-C of the carbohydrate backbone (c) substitution