Nucleoside und Nucleotide. Teil 11. Phosphorylierung von 1‐(2′‐Desoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridon und dessen Verhalten bei der Synthese von Dinucleotiden

Nucleosides and Nucleotides, Part 11. Phosphorylation of 1‐(2′‐Desoxy‐β‐D‐ribofuranosyl)‐2(1 H )‐pyridon and its Behaviour in the Synthesis of Dinucleotides The behaviour of the unnatural nucleoside 1‐(2′‐deoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridon (Π d , 1 ) in the synthesis of dinucleotides with purine deoxynucleotides was studied. The optimized preparation of the protected dinucleoside phosphates (MeOTr) Π d pG ( 5 ) and (MeOTr) Π d pA ( 7 ) using the diester method of Khorana with DCC as condensing agent is described. The removal of the N‐acyl‐ and p‐methoxytrityl groups was effected by successive treatment with conc. ammonia solution and acetic acid/water 1:1 at 23° yielding the free dinucleoside phosphates Π d pG d ( 9 ) and Π d pA d ( 11 ). In a similar way, starting from (CNEt) pΠ d ( 15 ), the dinucleotides pΠ d pG ( 16 ), pΠ d pG d ( 18 ), pΠ d pA ( 17 ) and pΠ d pA d ( 19 ) were synthesized. The nucleotide 1‐(5′‐O‐Phosphoryl‐2′‐deoxy‐β‐D‐ribofuranosyl)‐2(1H)‐pyridon (pΠ d , 3 ) was prepared in excellent yield by selective phosphorylation of Π d ( 1 ) using phosphorylchloride in triethyl phosphate at −40°. Deoxyadenosine was phosphorylated in the same way. The compounds were characterized by UV. spectroscopy, chromatography and enzymatic degradation.