PTERIDINES .94. SYNTHESIS AND CHARACTERISTICS OF 5,6-DIHYDRO-6-(1,2,3-TRIHYDROXYPROPYL)PTERIDINES - COVALENT INTRAMOLECULAR ADDUCTS

Pteridines: Synthesis and Characteristics of 5,6‐Dihydro‐6‐(1,2,3‐trihydroxypropyl)pteridines: Covalent Intramolecular Adducts 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). Copyright © 1990 Verlag GmbH & Co. KGaA, Weinheim