A novel one-pot three-component reaction: Synthesis of triheterocyclic 4H-pyrimido[2,1-b]benzazoles ring systems

Clean Synthesis in Water: Uncatalyzed Three‐Component Condensation Reaction of 3‐Amino‐1,2,4‐triazole or 2‐Aminobenzimidazole with Aldehyde in the Presence of Activated CH‐Acids

“…The structures of compounds 6a -m were deduced from their IR, 1 H NMR, and 13 C NMR spectra. The mass spectra of these compounds displayed molecular ion peaks at appropriate m/z values (Scheme 2).…”

“…NMR spectra were obtained on solutions in DMSO-d 6 . All the products are new compounds, except (12c, 11d) [13] which were characterized by IR, 1 H NMR, and 13 C NMR (because of low solubility of compounds (11f, 11h, 11i)…”

Agar: a novel, efficient, and biodegradable catalyst for the one-pot three-component and green synthesis of 2,3-dihydroquinazolin-4(1H)-one, 4H-pyrimidobenzothiazole and 2-aminobenzothiazolomethylnaphthol derivatives

“…The crude product was recrystallized from ethanol to afford the pure 4H-pyrimido [2,1-b] [1,3]benzothiazole derivatives. The desired pure products were characterized by comparison of their physical data (melting points, IR and 1 H NMR) with those of known compounds in the literature [40][41][42][43][44].…”

Synthesis and antimicrobial activity of 2H-pyrimido[2,1-b]benzothiazol-2-ones

“…In view of the diverse rang of biological activities of pyrimidobenzothiazoles and our continuing interest in the design and synthesis of nitrogen and sulphur-containing bioactive heterocycles [17][18][19][20], it was considered interesting to synthesize hitherto unknown pyrimido [2,1-b]benzothiazoles in order to evaluate their antimicrobial activities. The synthesis of pyrimido [2,1-b]benzothiazoles has already been reported in the literature by annulation protocols involving two steps (via amidation of 2-aminobenzothiazoles) [14] or by multicomponent reactions [21][22][23][24][25][26], but in the present work we have synthesized pyrimido [2,1-b]benzothiazoles by a simple and convenient regioselective one-pot synthesis by the reaction of 2-aminobenzothiazole with alkynoic acid. All the synthesized pyrimido[2,1-b]benzothiazole-2-ones are new compounds and their structures have been characterized by IR, 1 H NMR, 13 C NMR, and mass spectral data.…”