title: Purine studies. Part XX. Methylation and reduction of 2,8-dioxo-, 2,8-diamino-, and 2-amino-8-oxo-purines, and the stereochemistry of their 1,4,5,6-tetrahydro-derivatives.
mesh_terms: D006900:Hydroxylation; D008722:Methods; D008745:Methylation; D010084:Oxidation-Reduction; D011687:Purines / Q000138:chemical synthesis*; D012530:Saxitoxin / Q000031:analogs & derivatives*
chemical_list: D011687:Purines; D012530:Saxitoxin