Über Pterinchemie 51. Mitteilung [1] CNDO‐Rechnungen an Pterin, 6,7‐Dimethyl‐7,8‐dihydropterin und 5‐Formyl‐6, 7‐dimethyl‐5,6,7,8‐tetrahydropterin

Abstract

The 13C‐NMR.‐spectra of 7,8‐dihydropterines and 5,6,7,8‐tetrahydropterines show a large difference in the chemical shifts of the 4a‐ and 8a‐sp2‐carbon atoms. From the CNDO calculations it is apparent that there is a considerable difference in electron density at C(4a) and C(8a) atoms, which leads to a strong polarity of the CC‐Bond. The electron distribution in the highest occupied molecular orbital (HOMO) is discussed.

A DFT Study on the One‐Electron Reduction/Oxidation of Biologically Relevant Pteridine Derivatives

“…From a chemical point of view, the character of pteridine derivatives as pyrazino‐2,3d‐pyrimidines, containing 4 ring nitrogen atoms, leads to quite a complex chemical behaviour. Thus, they have early attracted the interest of theoretically minded chemists, and during the last two decades of the 20th century, a number of papers described results of quantum chemical work on various biologically and/or chemically interesting pteridine derivatives Most of these earlier papers employed ab initio quantum chemical procedures confined to Hartee‐Fock method using rather small basis function sets or even resorted to semi‐empirical methods.…”

Über Pterinchemie. 58. Mitteilung [1]. Sterische Eigenschaften von acylierten 5,6,7,8‐Tetrahydropterinen. Rotameren von 5‐Trifluoracetyl‐tetrahydropterin‐Derivaten

“…Massenspektren (MS.) : Angabe der Pike in m/e (rel.%). NMR.-Spektren: Angabe der chemischen Verschiebungen in ppm bezogen auf externes Tetramethylsilan (=0 ppm); Kopplungskonstanten J in Hz;s=Singulett,d=Dublett,t=Triplett,m= Multiplett,5,6,7,. 250 mg kristallines I a [2] werden unter Nz und Feuchtigkeitsausschluss in 30 ml Essigsaureanhydrid aufgeschlammt, 0,3 ml Trifluoressigsaure-anhydrid als Katalysator zugesetzt [7] und leicht erwarmt, bis alles gelost ist.…”

“…2H]-3,5,tetrakis(trifluoracety1)-5,6,7,8-tetrahydropterin (If ). If wird wie oben, ausgehend von [6-2H]-…”