Dergiler / Turkish Journal of Chemistry / 2015 / Cilt: 39 - Sayı: 6
Synthesis, characterization, and microwave-assisted catalytic activity in Heck, Suzuki, Sonogashira, and Buchwald--Hartwig cross-coupling reactions of novel benzimidazole salts bearing N-phthalimidoethyl and benzyl moieties
- Sayfa
- 1265–1278
- DOI
- —
Özet
Five novel benzimidazole salts (\textbf{1}--\textbf{5}) having N-phthalimidoethyl and 4-substituted benzyl were synthesized and identified by $^{1}$H NMR, $^{13}$C NMR, and IR spectroscopic methods and microanalysis. A mixture of the benzimidazole salts (\textbf{1}--\textbf{5}), Pd(OAc)$_{2}$, and K$_{2}$CO$_{3}$ in DMF-H$_{2}$O catalyzed, in high yield, the Suzuki--Miyaura and the Heck--Mizoroki cross-coupling reactions assisted by microwave irradiation in 5 min. The novel benzimidazole salts (\textbf{1}--\textbf{5}), Pd(OAc)$_{2}$, Cs$_{2}$CO$_{3}$, PEG, and Cu nanoparticles catalyzed, in high yield, the Sonogashira coupling reaction promoted by microwave irradiation in 10 min. The same benzimidazole salts (\textbf{1}--\textbf{5}), Pd(OAc)$_{2}$, Cs$_{2}$CO$_{3}$, and TBAB catalyzed, in moderate or low yield, the Buchwald--Hartwig reaction assisted by microwave irradiation in 60 min. The efficiency of the catalyst system in these four reactions was discussed as well as the electron-releasing and withdrawing substituent effects on the benzimidazole ligands.
Abstract
Five novel benzimidazole salts (\textbf{1}--\textbf{5}) having N-phthalimidoethyl and 4-substituted benzyl were synthesized and identified by $^{1}$H NMR, $^{13}$C NMR, and IR spectroscopic methods and microanalysis. A mixture of the benzimidazole salts (\textbf{1}--\textbf{5}), Pd(OAc)$_{2}$, and K$_{2}$CO$_{3}$ in DMF-H$_{2}$O catalyzed, in high yield, the Suzuki--Miyaura and the Heck--Mizoroki cross-coupling reactions assisted by microwave irradiation in 5 min. The novel benzimidazole salts (\textbf{1}--\textbf{5}), Pd(OAc)$_{2}$, Cs$_{2}$CO$_{3}$, PEG, and Cu nanoparticles catalyzed, in high yield, the Sonogashira coupling reaction promoted by microwave irradiation in 10 min. The same benzimidazole salts (\textbf{1}--\textbf{5}), Pd(OAc)$_{2}$, Cs$_{2}$CO$_{3}$, and TBAB catalyzed, in moderate or low yield, the Buchwald--Hartwig reaction assisted by microwave irradiation in 60 min. The efficiency of the catalyst system in these four reactions was discussed as well as the electron-releasing and withdrawing substituent effects on the benzimidazole ligands.