A NEW ROUTE TO SOME ENANTIOMERICALLY PURE SUBSTITUTED MORPHOLINES FROM D-RIBONO- AND D-GULONO-1,4-LACTONES

D-Ribono-1,4-lactone, after acetalation, tritylation, and reduction, leads to a cyclization compound which gave with tosyl chloride 1,4-anhydro-2,3-O-isopropylidene-5-O-trityl-D-ribitol. The latter was transformed (acid hydrolysis, periodate oxidation, reduction, tritylation, and tosylation) into a ditosylated derivative 16, which was cyclized into morpholines by the action of primary amines. Acid hydrolysis, followed by acetylation, gives the (2S)-acetoxymethyl-4-isopropyltetrahydro-1,4-oxazine (21). A similar sequence has been applied to D-gulonolactone to give access to oxazines 33, 34, and 35.