Toluene-4-sulfonic acid (5R,6R,8R,9R)-4-amino-9-(tert-butyl-dimethyl-silanyloxy)-8-(3,5-dimethyl-2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-2,2-dioxo-1,7-dioxa-2λ
6-thia-spiro[4.4]non-3-en-6-ylmethyl ester                                                                                                                                                              在
                                                                                                                                                                                 
potassium carbonate                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
乙腈                                                                                  为溶剂,
                                                                                                                                                    反应 6.0h,
                                                                                                                以68%的产率得到5',N
4''-cyclo[1-[2'-O-tert-butyldimethylsilyl-5'-amino-5'-deoxy-β-D-ribofuranosyl]-3-N-methylthymine]-3'-spiro-5''-(4''-amino-1'',2''-oxathiole 2'',2''-dioxide)