142102-80-5 2',5'diSilySpiroT AIDS-003919 AIDS003919 TSAO-e3T TSAO-e^3T Thymidine, 3-ethyl, [2',5'-bis-O-(tert-butyldimethylsilyl)-.beta.-D-ribofuranosyl]-3'-spiro-5-(4-amino-1,2-oxathiole-2,2-dioxide)