Quinazolines isatoic anhydrides with amines

A similar rapid microwave one-pot synthesis of substituted quinazolin-4-ones was also reported, which involved cyclocondensation af anthranilic acid, formic acid (or an orthoester) and an amine under solvent-free conditions (Scheme 3.37)61. A complimentary approach was adopted to synthesise 4-aminoquinazolines in very good yields, involving the reaction of aromatic nitrile compounds with 2-aminobenzonitrile in the presence of a catalytic amount ofbase (Scheme 3.38)62. The reactions were performed in a domestic microwave oven and required only a very short heating time. A microwave-assisted synthesis of a variety of new 3-substituted-2-alkyl-4-(3H)-quinazolinones using isatoic anhydride, 2-aminobenzimidazole and orthoesters has also been described (Scheme 3.38)63. 

In a one-pot synthesis, treatment of isatoic anhydrides 13 with ammonia, phosphoryl chloride, and a primary amine in dimethylformamide gives high yields of quinazolin-4-amines 16. The intermediates 14 and 15 can be isolated if desired. This method appears to be a general, one-pot method for the synthesis of quinazolin-4-amines in good yields. ... 

A study of all the stages in the synthesis of 4-aminoquinazolines from isatoic anhydride, via anthranilamide and o-aminobenzonitrile, made possible the preparation of these compounds by a one-pot synthesis. The anhydride was treated with ammonia in dimethylformamide, nitrogen was then bubbled through the solution to remove excess of ammonia, phosphoryl chloride was added and heated at 40°-60°C for conversion into the nitrile, and finally the respective amine was added to yield the 4-(substituted-amino)-quinazolines in 44-79% yields. ... 

The mono- and disubstituted quinazolin-4(3/7)-one derivatives were firstly synthesized under solvent-free conditions by one-pot three-component reaction of isatoic anhydride, ortho ester, and anunonium acetate or an aliphatic and aromatic primary amine in the presence of SSA (Salehi et al., 2005) (Scheme 5.8). After completion of the reaction, the crude mass was diluted with hot ethanol and filtered. The filtrate was concentrated and products were purified by recrystallization from ethanol. Solvent-free... 

A convenient method for the synthesis of 3-substituted quinazolin-4(3H)- ones using the convergent reactions of formic acid, a primary amine, and isatoic anhydride under solvent-free conditions and with brief microwave irradiation is described. 

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