New Synthetic Potential of Pteridine Derivatives: Direct Substitution of H in 1,3-Dimethyllumazine During Reaction with C-Nucleophiles

One-Pot Synthesis of 7-(Benzimidazol-2-yl)thioxolumazine and -lumazine Derivatives via H2SO4-Catalyzed Rearrangement of Quinoxalinones When Exposed to 5,6-Diamino-2-mercapto- and 2,5,6-Triaminopyrimidin-4-ols

“…The first is a two-stage process involving the introduction of a C6 side chain via Sonogashira coupling of a pteridine derivative with alkynyl alcohols, which affords alkynyl-pteridines, which can be transformed into triazoles by Huisgen–Sharpless 1,3-dipolar cycloaddition . The second method involves direct nucleophilic substitution of H in C(7) unsubstituted 1,3-dimethyllumazine with C-nucleophiles (indoles, 3-methyl-1-phenylpyrazolone-5) in the presence of acids to give the indol-3-yl and pyrazol-5-on-4-yl derivative of lumazine . Thus, there is no general method for the synthesis of compounds containing a heterocyclic ring system directly bonded to pteridine.…”

Direct C–H/C–H Coupling of the Azoloannulated Pteridines with Electron Rich (Hetero)Aromatic Compounds

“…In both cases, the product of monosubstitution was formed as a result of pteridine activation by acid. It should be noted that in a previous work, the substitution occurs exclusively at the pyrazine ring rather than at pyrimidine cycle (Scheme b). In addition, the authors were also able to isolate and characterize the intermediate σ H -adducts.…”

“…To the best of our knowledge, there are only two examples of pteridine modification by the S N H AO methodology (Scheme a,b) , represented in the literature. In both cases, the product of monosubstitution was formed as a result of pteridine activation by acid.…”

“…21−23 The nucleophilic substitution of hydrogen mechanism consists of the direct attack by the nucleophile to the CH-fragment of the electron-deficient molecule with the formation of the σ H -adduct, which can subsequently be converted into the aromatic structure via oxidative (S N H AO) or eliminative (S N H AE) pathways. 23 To the best of our knowledge, there are only two examples of pteridine modification by the S N H AO methodology (Scheme 1a,b) 24,25 represented in the literature. In both cases, the product of monosubstitution was formed as a result of pteridine activation by acid.…”

Transition-Metal-Free С–С Coupling of 5,7-Dihydroxybenzopyrones with Quinoxalones and Pteridinones

“…Another synthetic way to pteridine and quinoxaline analogues 7 is a direct nucleophilic substitution of hydrogen atom (S N H ) in the pyrazine ring. The formation of C-C bonds through the S N H reactions has received a great attention of chemists due to the recently advanced concept of green chemistry based on using pot-, atom-, and step-economical (PASE) reactions.…”