Abstract
The first total synthesis of the 8-oxopurine 8, a constituent of the marine sponge Hymeniacidon sanguinea GRANT, has been achieved via two alternative routes starting from 8-bromo-9-methyladenine (11), which is obtainable from 9-methyladenine (10) by bromination. The first route includes methylation of 11 with MeI to give the 1-methylated product 13·HI, conversion of 13·HI into the free base 13, and treatment of 13 with NaOAc in boiling AcOH to produce 8 in 25% overall yield (from 10). The second route includes treatment of 11 with boiling 1 N aqueous NaOH and methylation of the resulting 8-oxo derivative 12 with MeI, affording 8 in 63% overall yield (from 10). The rearranged isomer 15 and the N6 -acetyl derivative 9 have also been synthesized.
