SYNTHESIS OF A HYDROGEN-BOND-DEGENERATE TRICYCLIC PYRROLOPYRIMIDINE NUCLEOSIDE AND OF ITS 5'-TRIPHOSPHATE

The syntheses of a number of 7-(2-deoxyribofuranosyl)pyrrolo[2,3-d]pyr imidine derivatives are described. Of these the 2-methylsulfanyl-4-hyd roxy-5-acetoxyethyl derivative 7 was conveniently formed by condensati on of 2-methylsulfanyl-4-hydroxy-6-aminopyrimidine with 2-chloro-4-ace toxybutanal 6; it was then converted to the 4-chloro derivative 12 wit h phosphoryl trichloride and coupled to 3,5-di-p-toluoyl-2-deoxy-alpha -ribosyl chloride. Transformation to the 5-aminooxyethyl derivative an d ring closure of the latter gave the tricyclic hylsulfonyl-7-oxa-2,3, 5,6-tetraazabenz[cd]azulene. Hydrazinolysis of the methylsulfonyl resi due, then mercury(II) oxide oxidation, led to the target nucleoside 4. For its study as a polymerase substrate for incorporation into DNA th e 5'-triphosphate was synthesised.