5-Arylthio-tetrazolo[1,5-c]quinazolines (tautomers of 2-arylthio-4-azido-quinazolines) undergo facile nucleophilic aromatic substitution reactions with amines, alcohols and alkylthiols. This, combined with recently reported arylsulfanyl group dance, provides a straightforward access to 4-azido-2-N-, O-,...

Nucleophilic aromatic substitution reaction between 4-aryl­thio-2-chloroquinazolines and NaN3 takes place with an unusual sulfanyl group dance and leads to the formation of 5-(arylthio)tetrazolo[1,5-c]-quinazolines, which do not form the azide tautomer and do not undergo CuAAC reactions with alkynes. On the other hand, 5-azidotetrazolo[1,5-a]quinazoline (formally described as 2,4-diazidoquinazoline) undergoes regioselective nucleophilic aromatic substitution with thiols at C5 and forms 5-(alkyl/arylthio)tetrazolo[1,5-a]quinazolines, the structure of which has been proved by X-ray crystallography. The latter exist in tautomeric equilibrium with their 2-azidoquinazoline form, which provides possibility for copper-catalyzed azide–alkyne 1,3-dipolar cyclo­addition reaction, leading to the 4-alkyl/arylthio-2-(1H-1,2,3-triazol-1-yl)quinazolines.

A ratiometric fluorescence cation sensor based on an asymmetrically functionalized donor–acceptor–donor′ purine derivative is presented.

Here, we describe detailed synthetic protocols for preparation of 6amino/thio-2-triazolylpurine ribonucleosides. First, 9-(2 ,3 ,5 -tri-O-acetyl-β-D-ribofuranosyl)-2,6-diazido-9H-purine, to be used as a key starting material, is synthesized in an S N Ar reaction with NaN 3 starting from commercially available 9-(2 ,3 ,5 -tri-O-acetyl-β-D-ribofuranosyl)-2,6-dichloro-9H-purine. Next, 2,6-bis-triazolylpurine ribonucleoside is obtained in a CuAAC reaction between diazidopurine derivative and phenyl acetylene, and used in S N Ar reactions with N-and S-nucleophiles. In these reactions, the triazolyl ring at the purine C6 position acts as a good leaving group. Cleavage of acetyl protecting groups from the ribosyl moiety is achieved in presence of piperidine. In the S N Ar reaction with amino acid derivatives, the acetyl groups remain intact. Moreover, 9-(2 ,3 ,5 -tri-O-acetyl-β-D-ribofuranosyl)-2,6-diazido-9H-purine is selectively reduced at the C6 position using a CuSO 4 •5H 2 O/sodium ascorbate system. This provides a straightforward approach for synthesis of 9-(2 ,3 ,5 -tri-O-acetyl-β-D-ribofuranosyl)-6-amino-2-azido-9H-purine.