Convergent One‐Pot Synthesis of 3‐Substituted Quinazolin‐4(3H)‐ones under Solvent‐Free Conditions

More Sustainable Approaches for the Synthesis of N-Based Heterocycles

“…Despite a high excess of formamide (5 equiv) that has to be used in order to improve the reaction yield, this procedure can also be efficiently applied for the synthesis of tetracyclic 8 H -quinazolino[4,3- b ]quinazolin-8-ones . Recently, 3-substituted quinazolin-4(3 H )-ones were also reported to be synthesized under MWI through this method forming the formamide in situ through the presence of formic acid and a primary amine …”

“…778 Recently, 3-substituted quinazolin-4(3H)-ones were also reported to be synthesized under MWI through this method forming the formamide in situ through the presence of formic acid and a primary amine. 779 The employment of isatoic anhydride, instead of anthranilic acid, also leads to the formation of 2,3-disubstituted quinazolin-4(3H)-ones under conventional heating in presence of amines and orthoester derivatives using silica sulfuric acid as catalyst 780 (Table 121). Instead of silica sulfuric acid, diammonium hydrogen phosphate can be used as catalyst at the same temperature for 5-7 h. 181 As a method to manipulate the N-3 substituent, ammonium acetate can be used under these reaction conditions 781 or by microwave-induced cyclocondensation of anthranilic acid without catalyst.…”

Efficient and Practical One-Pot Route to Synthesise Quinazolin4(3H)-Ones Using Trifluoromethanesulfonic Anhydride and 2-Chloropyridine

“…The combination of trifluoromethanesulfonic anhydride (Tf 2 O) and pyridine or 2-chloropyridine (2-ClPy) is the most attractive and feasible example. [16][17][18] We believed that the combination of trifluoromethanesulfonic anhydride (Tf 2 O) and 2-chloropyridine (2-ClPy) would be useful for our purpose. The three component one-pot condensation of isatoic anhydride 1, benzoyl chloride 2a, and aniline 3a was selected as a model reaction.…”

Synthesis of a series of carbon‐14 labelled 4‐aminoquinazolines and quinazolin‐4 (3H)‐ones

“…In both cases however, to ensure optimum yield of products, an excess of formic acid 8 had to be employed. [14][15][16] On the other hand, using the known Niementowski reaction, 17,18 the condensation of formamide 9 with 6a under microwave irradiation, gave the desired product 2 in a few minutes.…”