A fascinating click strategy to novel 1,2,3-triazolium based organic-inorganic hybrids for highly accelerated preparation of tetrazolopyrimidines

Abstract

Herein, click reaction is used for the preparation of novel organic-inorganic Brønsted acidic ionic solids (BAISs) as new catalysts for the efficient synthesis of tetrazolopyrimidines. A series of mono and disubstituted-1,2,3-triazoles were synthesized under click reaction condition. The prepared 1,2,3-triazoles underwent reaction with 1,4-butanesultone to provide novel solid 1,2,3-triazolium N- butyl sulfonate zwitterions. Then, the reaction of phosphotungstic acid with the obtained zwitterions led to the novel 1,2,3-triazolium-N-butyl sulfonic acid phosphotungstate as acidic ionic solids. The synthesized BAIS catalysts were fully characterized using FTIR, 1H and 13C NMR, XRD, elemental analysis (CHNS), TG and DSC techniques. The introduced novel hybrids were used as efficient catalysts for the synthesis of targeted methyl-7-aryl-4,7-dihydrotetrazolo[1,5-a]pyrimidine-6-carboxylate and 6,6-dimethyl-9-aryl-5,6,7,9-tetrahydrotetrazolo[5,1-b]quinazolin-8(4H)-one derivatives via multicomponent reaction of aromatic aldehydes, active methylene compounds and 5-aminotetrazole. Low amount of the prepared 1,2,3-triazolium-N-butyl sulfonic acids phosphotungstate catalysts (5–10 mmol%) gave desired products in short times (20–45 min) with excellent yields (87–93%). Novelty of the introduced catalysts, ease of recovery and reusability up to four repeated runs with no significant decrease in the yields are highlighted superiorities of the introduced organic-inorganic hybrid catalysts.