| 主权项 |
1. A method for preparation of the compound of formula 1, comprising the following steps: reacting compound 4 with 2-protected amino-6-substituted purine compound 5 to give the coupling reaction product 6 wherein R1 and R2, which are the same or different, are independently selected from hydroxy-protecting groups of the following Groups (i) to (iii): (i) R1 and R2, independent of each other, are selected from alkyl, halo-alkyl, benzyl, t-BuMe2Si, t-BuPh2Si, (i-Pr)3Si or Et3Si; or (ii) R1 and R2, independent of each other, are selected from t-BuMe2Si, t-BuPh2Si, benzoyl, tetrahydropyran-2-yl, benzoyl in which the phenyl ring bears substituent(s), and biphenyl-4-formyl, provided that R1 and R2 are not both t-BuMe2Si; R and R′, which are the same or different, are independently selected from hydrogen, alkoxycarbonyl or aralkoxycarbonyl, provided that R and R′ are not both hydrogen; X is halo, alkoxy, halo-alkoxy or aralkoxy; Thereafter when R1 and R2 are both acyl protective groups or neither of them is acyl protective group, removing hydroxy-protecting groups from compound 6, to give compound 7 wherein X, R1, R2, R and R′ are defined as above; Thereafter hydrolysis of compound 7 to give the compound of formula 1 or when neither of R1 and R2 is acyl protective group, deprotecting compound 6 while hydrolysis in one-pot manner, to directly yield the compound of formula 1 wherein X, R1, R2, R and R′ are defined as above, or when one, but only one of R1 and R2 is acyl protective group, deprotecting compound 6 to give compound 8 which is then hydrolyzed to give compound 1 or is converted to compound 7 followed by hydrolysis to give compound 1. |
