One‐Pot Synthesis of Imidazole‐4‐Carboxylates by Microwave‐Assisted 1,5‐Electrocyclization of Azavinyl Azomethine Ylides

Abstract

Diversely functionalized imidazole-4-carboxylates were synthesized by microwave-assisted 1,5-eletrocyclization of 1,2-diaza-1,3-diene-derived azavinyl azomethine ylides. 1,2-Diaza-1,3-dienes were treated with primary aliphatic or aromatic amines and subjected to microwave irradiation in the presence of aldehydes. 3-Alkyl- and 3-arylimidazole-4-carboxylates were prepared in good yields through a one-pot multicomponent procedure. Modulation of the substituents at C-2, N-3 and C-5 was possible, and 2-unsubstituted imidazoles were obtained when paraformaldehyde was used.

Metal and Oxidant Free Construction of Substituted‐ and/or Polycyclic Indoles: A Useful Alternative to Bischler and Related Syntheses

“…N ‐benzyl‐4‐methoxyaniline 1e were prepared according to the reported method . 1,2‐Diaza‐1,3‐dienes 2a–g,k,l were synthesized as a mixture of E/Z isomers as previously reported . Chromatographic purification of compounds was carried out on silica gel (60–200 µm).…”

Heteroring‐Annulated Pyrrolino‐Tetrahydroberberine Analogues

“…As olution of 1,2-diaza-1,3-dienes 4a-j (0.5 mmol) as am ixture of EE/EZ isomers [18] and 7,8-dihydroberberines 2 or 3 (0.5 mmol) was stirred in acetonitrile (1.5 mL) at room temperature for 0.25 h, until the disappearance of the reagents and the formation of compounds 6 (TLC). Products 6e, 6f, 6k and 6l directly precipitated from the reaction medium, whereas in the other cases, the solvent was evaporated under reduced pressure at 25 8Ca nd the crude mixtures were then subjected to column chromatography on aluminum oxide (cyclohexane/EtOAc mixtures) to afford products 6ad and 6g-j,w hich were crystallized by concentrating the corresponding column fractions under vacuum at 25 8C.…”

“…Anhydrous berberine chloride was obtained by heating the corresponding hydrate (ca. 17 %w /w H 2 O), at 50 8Cu nder vacuum for 8h.1 ,2-Diaza-1,3-dienes were prepared as reported18 and used as EE/EZ isomers mixtures. Melting points were determined in open capillary tubes and are uncorrected.…”

Microwave-assisted synthesis of phenanthroimidazole derivatives as stabilizer of c-myc G-quadruplex DNA

“…1) have been synthesized with yield of 87% under microwave irradiation. 12 It's found that this class of compounds, especially 5 can inhibit the growth of various tumor cells, especially MDA-MB-231 cells. The binding behavior of 5 with c myc G4 DNA have been investigated by spectroscopy methods, FRET and PCR-stop assay, and the results show that 5 can stabilize the G-quadruplex structure and inhibit the replication of c-myc oligomers.…”