Nucleotides. Part XXVIII. Chemical syntheses of the 2′‐5′‐cordycepin‐trimer core

The chemical synthesis of 3′‐deoxyadenyly‐(2′‐5′)‐3′‐deoxyadenylyl‐(2′‐5′)‐3′‐deoxyadenosine ( 30 ; trimeric cordycepin) is described by three different routes using various protecting groups and applying the phosphotriester approach. The intermediates have been isolated and characterized by elemental analyses and spectroscopic means. High yields of 30 have been obtained on deprotection making this biologically very active compound available in preparative scale.