3'-Spiro nucleosides, a new class of specific human immunodeficiency virus type 1 inhibitors: synthesis and antiviral activity of [2', 5'-bis-O-(tert-butyldimethylsilyl)-.beta.-D-xylo- and -ribofuranose]-3'-spiro-5''-[4''-amino-1'', 2''-oxathiole 2'', 2''-dioxide] (TSAO) pyrimidine nucleosides | doi.page