AIDS-006831 AIDS006831 TSAO 1,2,3-triazole deriv. [1-[2',5'-Bis-O-(tert-butyldimethylsilyl)-.beta.-D-ribofuranosyl]-5-[(methoxy)carbonyl]-1,2,3-triazole]-3'-spiro-5-(4-amino-1,2-oxathiole 2,2-dioxide)