Pteridines: Synthesis and characteristics of 5,6-dihydro-6-(1,2,3-trihydroxypropyl)pteridines: Covalent intramolecular adducts

Article abstract of DOI:10.1002/hlca.19900730407

Various 5,6-diaminopyrimidines (1, 15, 24, 33) were condensed with the phenylhydrazones of L-(2) and D-arabinose (3) in acidic medium under N₂ to give formal 5,6-dihydro-6-(1,2,3-trihydroxypropyl)pteridines (see, e.g., 4 and 5), the latter turned out to exist preferentially as intramolecular adducts, the hexahydropyrano-[3,2-g]pteridines 6, 7, 16, 17, 25, 26, and 34, formed subsequently by addition of the terminal OH group of the side-chain to the C(7)=N(8) bond of the pteridine moiety. Spectroscopically, the isomeric hexahydrofuro [3,2-g]pteridines 10, 11, 18, 19, and 35 were also detected as minor components in the equilibrium mixtures. In the 4-amino-2-(methylthio)pteridine series, crystallization of 6 and 7 led to the stereochemically pure (3S,4R,4aR,10aS)-6-amino-3,4,4a,5,10,10a-hexahydro-8-(methylthio -2H-pyrano[3,2-g]pteridine-3,4-diol (8) and its corresponding enantiomer 9, respectively. Structure 8 was proven by X-ray analysis. Acylation of the hexahydropyrano[3,2-g]pteridines yielded the more stable tri-, tetra-, and pentaacetyl derivatives 12-14, 20-23, 27-32, and 37-39 which were characterized and of which the absolute and relative configurations were determined (¹H- and ¹³C-NMR and UV spectra, chiroptical measurements, elemental analyses).