NUCLEOTIDES .47. SYNTHESIS OF 3'-DEOXYADENYLYL-(2'-5')-3'-DEOXYADENYLYL-(2'-5')-3'-O-(2-HYDROXYETHYL)ADE NOSINE AND 3'-DEOXYADENYLYL-(2'-5')-3'-DEOXYADENYLYL-(2'-5'-3'-O-(2-[(CHOLEST-5-EN-3- BETA-YLOXY)CARBONYLOXY]ETHYL)ADENOSINE - A NEW TYPE OF (2'-

摘要

A suitably protected adenosine derivative bearing an acetyl-protected 2-hydeoxyethyl moiety in 3'-O-position was attached to the 2'-terminus of a cordycepin (3'-deoxyadenosine) dimer. Coupling was performed by phosphoramidite chemistry using two alternative approaches - condensation of 5'-phosphoramidite 16 with 2'-OH cordycepin dimer 18 and condensation of dimeric cordycepin phosphoramidite 19 with 5'OH adenosine derivative 15 - of which the latter synthesis worked best (-->20). After cleavage of the acetyl protecting group (-->21), cholesteryl carbonate was introduced into the OH function of the spacer (-->24). Final deblocking of trimer 24 with, or trimer 21 without the cholesterol moiety afforded the modified cordycepin conjugates 25 and 23, respectively. [References: 33]