.beta.-D-Allopyranoside, 2-(dimethylamino)-3a,5,6,6a-tetrahydro-4-hydroxy-6-(phenylmethoxy)methyl-4H-cyclopentoxazol-5-yl 2-deoxy-4-O-2-deoxy-2-(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)-3-O-(phenylmethyl)-4,6-O-(phenylmethylene)-.beta.-D-allopyranosyl-2-(1