.beta.-D-Allopyranoside, 2-(dimethylamino)-3a,5,6,6a-tetrahydro-6-hydroxy-4-(hydroxymethyl)-4H-cyclopentoxazol-5-yl 2-(acetylamino)-4-O-2-(acetylamino)-2-deoxy-.beta.-D-allopyranosyl-2-deoxy-, 3aS-(3a.alpha.,4.alpha.,5.beta.,6.alpha.,6a.alpha.)-