SYNTHESIS AND REACTIONS OF NEW DERIVATIVES OF FURO[3,2-b]PYRROLE

Abstract

Synthesis of methyl 4H-furo[3,2-b]pyrrole-5-carboxylate is taken place in two step synthesis. Vilsmeier-Haack reaction of 4H-furo[3,2-b]pyrrole-5-carboxylate 1 led to methyl 2-formyl-4H-furo[3,2- b]pyrrole-5-carboxylate 4, which served as starting compound for synthesis of furo[3,2-b]pyrrole-2- aldoxime 5 and methyl 2-[(4-oxo-2-thioxo-1,3-thiazolidin-5-ylidene)methyl]-4H-furo[3,2-b]pyrrole-5- carboxylate 7. The hydrazinolysis of 1 was prepared by carbohydrazide 2, which subsequently reacted with aldehydes to form of derivatives 3. Pyrazole derivatives 11 were prepared by the reaction of azlactone 9 with derivatives 10. Reactions were carried out under microwave irradiation or at classical heating.

Synthesis and antibacterial activity of furo[3,2-b]pyrrole derivatives

“…Compound 1d displays in its 1 H NMR spectrum a singlet due to the NH group at 11.66 ppm, and singlets of H-6 and H-3 at 6.74 and 6.06 ppm, respectively. The 13 C NMR spectrum of 1d shows the signal of ester carboxyl carbon at 165.2 ppm. The proposed mechanism involves formation of pyrrole N-anion in the initial step of reaction, but the direct bond interaction between bulky tritylium ion and pyrrole N-anion would be thermodynamicaly unstable due to steric hindrance caused by the adjacent -COOMe group and the furane ring.…”

“…The structures of compounds 7 were established by 1 H NMR, 13 C NMR and IR spectroscopy. 1 H NMR spectra show doublets of H-6 protons at 7.11-6.78 ppm region (J 0.6 Hz), H-3 protons resonate either as doublets of doublets (7a) at 6.83 ppm (J 2.1, 0.9 Hz) or as singlets (7b, 7c) at 6.89 and 6.43 ppm, respectively.…”

“…The CH2 protons appear as singlets at 5.15-5.21 ppm. 13 C NMR spectra show ester carboxyl carbon signals of at 168.6-169.6 ppm and 161.5-162.1 ppm. The characteristic bands observed at 1747-1754 and 1685 cm -1 in IR spectra of 7b and 7c correspond to the ester carbonyl groups.…”

“…The structures of compounds 9 and 10 were established by 1 H NMR, 13 C NMR and IR spectroscopy. While 1 H NMR spectrum of 9 show no signal of NH group and one singlet signal of NH2 group at 5.31 ppm, in the spectra of 10a, 10b there is a singlet for one NH group at 10.41 ppm and no signals of NH2 groups were observed.…”

“…As part of our current studies on the development of new methods in heterocyclic synthesis, 13,14 we report an efficient synthesis of furo [3,2-b]pyrrole derivatives fused with six-membered rings and evaluation of the synthesized compounds as to their antibacterial activity.…”