AIDS-006849 AIDS006849 TSAO 1,2,3-triazole deriv. [1-[2',5'-Bis-O-(tert-butyldimethylsilyl)-.beta.-D-ribofuranosyl]-4-[(methoxy)carbonyl]-1,2,3-triazole]-3'-spiro-5''-[4''-(acetylamino)-1'',2''-oxathiole 2'',2''-dioxide]