1-(2',3'-Dideoxy-.beta.-D-glucopyranosyl)cytosine 136020-18-3 2',3'-Dideoxy-hexopyranosyl cytidine 2(1H)-Pyrimidinone, 4-amino-1-(2,3-dideoxy-b-D-erythro-hexopyranosyl)- AIDS-002941 AIDS002941 ddC analog