Nucleosides Part LXVI I[ 1 ]: Synthesis of 4-Amino-7(8H)Pteridinone-N8-Nucleosides—Structural Analogs of Adenosine

Various 4-amino-7(8H)pteridones (6, 12, 14, 15, 20, 22) have been glycosylated with 1-chloro-2′-deoxy-D-ribofuranose derivatives (25, 26) applying the new DBU-salt method to form the N8-2′-deoxy-D-ribofuranosides (27–36) which can be regarded as 2′-deoxyadenosine analogs. Analogously reacted the 2-N,N-dimethyl-amino-methyleneimino-7(8H)pteridones (43–48) to give preferentially the corresponding N8-s-D-anomers (49–55). Ribosylation with 1-bromo-2,3,5-tri-O-benzoyl-a-D-ribofuranose (56) proceeded as well with 6, 12, 15, 45, and 46 to yield to N8-s-D-ribofuranosides 57–61. Sugar deprotection led to the free N8-2′-deoxy-s-D-ribofuranosides 37–42 and N8-s-D-ribofurano-sides 62–65, respectively. Glycosylations via the silyl-method under Vorbruggen conditions led with 6, 12 and 15 to the same results, however, 4-amino-6-phenyl-7(8H)pteridone (14) reacted differently forming the N1-s-D-ribofuranosides (71, 79) and the N1-2′-deoxy-α-and s-D-ribofuranosides 73, 74, 77, 78. The assignments of the structures have bee...