Condensation of anthranilic acids

Table 3. Benzannulated 1,5-Diazocines by the Condensation of Anthranilic Acid Derivatives...

The gallium(lll) triflate-mediated condensation of anthranilic acid with fluorinated ketones gave the corresponding 2,2-disubstituted l,2-dihydro-4//-3,l-benzoxazin-4-ones in high yields <20070L179>. 

Condensations of anthranilic acid derivatives lead to the 6,12-diamino- and 6,12-dioxo-dibenzodiazocines, and the dichloro compound (279) is available from the latter (54JCS3429). Reduction of (279) via the dihydrazino compound was used to prepare the parent dibenzo[6,/][l,5]diazocine (280) (67CC1077). The NMR value (5 8.53 p.p.m.) of the 6(12) proton is indicative of the diazocine structure, presumably in a tub form, rather than the valence isomeric dibenzodiazapentalene (281). 

Condensation of anthranilic acid or its methyl ester with the 2,3-benzoxazine imidoyl chloride or imidate ester (569) gave the 5H, H-quinazo ino[3,2-c]2,3-benzoxazin-9-one (570) [74CI(M)492]. 

Developing their work on the use of microwave-assisted Niementowski reactions, the same group published the synthesis of novel triaza- and tetraaza-benzo a -indeno[l,2-c]anthracen-5ones by the condensation of anthranilic acid with 2-(2-aminophenyl)indole or benzimidazole (Scheme 3.49)78,79. 

Diazaanthracene derivatives were first obtained by condensation of anthranilic acid... 

Alternative suggestions for the construction of the furan ring have been made by Wenkert 154), who invokes a condensation of anthranilic acid with erythrose, and by Ghosal 159), who utilizes anthranilic acid and ornithine as precursors (see p. 262),... 

Condensation of anthranilic acid with various ort/zo-esters and reaction of semicarbazides, gave 2-substituted benzoxazin-4-ones and also by the reaction of hydrazones with aryl-/alkyl-ureas and by salicylaldehyde or 2-hydroxyacetophenones with 4-aryl-/alkyl-semicarbazides. Hydrolysis of o-aminoesters and subsequent treatment with phosgene gave 40. Fused oxazine with bridge head nitrogen 41 and triazolo[3,4-Z>]thiazines 42 were also prepared . The 2,3-dihydrobenzoxazine 43, thiomorpholines 44 and phenothiazines 45 were prepared. ... 

By condensation of anthranilic acid with ethyl phenyliminoacetate (52)... 

An efficient method for the synthesis of 2-substituted benzoxazin-4-ones was performed by the condensation of anthranilic acid (436) with various orthoesters by classical heating for 1 2h to give 75 91% yields. But under MWI in an open vessel, a rapid formation of benzoxazin-4-ones 439 in high yields (76-94%) took place within 1-5 min (Scheme 86). The reaction may proceed through the imidic ester intermediate 437, which upon nucleophilic attack by the carboxyl oxygen produced the cycKzed intermediate 438 that then eliminated a molecule of alcohol to give 439 (97JCR(S)286). 

Scheme 28.3.3 shows the synthesis of fenazaquin. The quinazoline ring is formed by the condensation of anthranilic acid with formamide and subsequent... 

The Niementowski synthesis, first described in 1895, remains one of the most important methods for synthesizing quinazolines and quinazolinones. This reaction involves condensation of anthranilic acids with formamide or acetamide derivatives to form the intermediate quinazoline-4(3//)-ones under thermal conditions. 

Many syntheses of (42) have been reported, but only three will be mentioned here (cf. 94). Chatterjee and Ganguly (40) reported the condensation of anthranilic acid and y-aminobutyric acid with phosphorus pentoxide in boiling xylene to give (42) in 50% yield, while refluxing anthranilic acid with O-methylbutyrolactim in benzene afforded (42) in 82% yield 146,161). Kametani et al. 108) synthesized (42) regiospecifically in good yield by treatment of the sulfinamide anhydride of anthranilic acid with O-methylbutyrolactim. Synthesis of (42) is also possible by oxidation of deoxyvasicine with hydrogen peroxide (cf. 94). 

The synthesis of quinolines and quinazolines via the Niementowski reaction has also been carried out using microwave conditions. Condensation of anthranilic acid 1 and ketones 32 and 33 under microwave irradiation gave products 34 and 35, respectively. 

An extension of the Niementowski reaction that has been used for the condensation of anthranilic acids with lactams has been reported by Sastry et al. Addition of phosphorous oxychloride at room temperature to a solution of lactam 46 was followed by addition of anthranilic acid (1). Subsequent stirring at room temperature followed by heating at reflux furnished products 48 in 60-90% yield. The reaction presumably proceeds via formation of 47 followed by condensation with anthranilic acid (1) and cyclodehydration to give 48. Additional examples of phosphorous oxychloride mediated 4-quinazolone syntheses with either anthranilic acid or the corresponding... 

Bls(4H-benzoxazin-4-one-2-yl)-galacto-tetritol tetraacetate (42) was obtained by condensation of anthranilic acid with the... 

The historical condensation of anthranilic acid (3) with phloroghicinol (206) to give 1,3-dihydroxyacridone (22) by Baczynski and von Niementowdd should be considered as Ae first biomimetic synthesis of an acridone alkaloid (284). The yield of the reaction was initially very poor, but was increased by subsequent modifications by Beck et al. (28S) and by Hlubucek et al. (286). More rec y. Smolders et al. described an efficient condensation of methyl anthranilate (207) with phloroglucinol, in the presence of 4-toluenesulfonic acid in l-hqitanol, which gave 22 in 80% yield (287). 

A microwave-assisted method has been developed by Ighilahriz et al. (2008) for the synthesis of 4(3H)-quinazolinones by condensation of anthranilic acid, orthoesters (or formic acid) and substituted anilines, using Keggin-type heteropolyacids upw p p3Up, H SiMOjP o-nnp or... 

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