3.1- Benzoxazine-2,4-diones anhydrides

The wide range of chemical transformations to which 2//-3,l-benzoxazine-2,4-dione (isatoic anhydride) 4 has been subjected is beyond the scope of this chapter. A review published a few years ago on the transformations of isatoic anhydrides to heterocyclic compounds contains valuable information on other aspects of the chemical behavior of these compounds <2001CHE385>. 

Isocyanatobenzoyl chloride reacted with isatoic anhydride (76JOC2728) or nitromethane in benzene [83IJC(B)485] to yield 5H,12H-quinazolino[3,2-a]3,1 -benzoxazine-5,12-dione (540) (76JOC2728). Cyclodehydration of 3-(2-carboxyphenyl)quinazoline-2,4(l//,3/f)-dione (575) (66ACH77 67MI1) also afforded the same compound (540). 

Pyrido[l, 2-a] [3,1 ]benzoxazine-l, 6-diones (191) were obtained by the cyclization of anthranilic acid derivatives (190) (89SC3103). Heating either anthranilic acid derivatives 192 or 193 in acetic anhydride afforded pyrido[l,2-a][3,l]benzoxazine-3,6-dione (194) in 33% and 55% yield, respectively (70KGS879). 

Benzoxazine-2,4-diones (43) (isatoic anhydrides) have proved useful synthons for various new heterocycles. For example, a base-catalyzed condensation with the oxindole (44) affords tetracycles (45) (80JHC1785), whereas the parent compound (43 R = H) and 3-hydroxyisothiazole give the quinazolinone (46) (69AJC2497). 

A strategy for producing unsymmetrical TB derivatives is based on the Wilcox synthetic protocol (Scheme 5). The reaction of aniline 4 with the derivative of isatoic anhydride, 3,l-benzoxazine-2,4(l//)-dione 5, or 2-nitrobenzoic acid 6 affords ami-noamide 7 and nitroamide 8, respectively. The reduction of 7 or 8 followed by a final cyclization reaction of bisamine 9 yields unsymmetrical TB derivatives 10 (90JOC363). 

The reaction of phthalic anhydrides 307 with trimethylsilyl azide affords l,3-benzoxazine-2,4-diones 308 in good yield (Scheme 168) <19950PP651, 1998JOC6797, CHEC-III(8.05.10)444>. 

H-3,1-Benzoxazine-2,4(1 H)-dione known as isatoic anhydride (VI) is the most popular six membered cyclic O-acyl carbamate. The synthesis of isatoic anhydride by ring closure of anthranilic acid with phosgene is well described (Ref. 250). However, we have developed an... 

Treatment of phthalic acid (145) with sodium azide under acidic conditions has been reported" to give various products anthranilic acid (147) and a trace of o-phenylenediamine (148) in concentrated sulfuric acid and anthranilazide (149) and benzimidazol-2-one (150) in 90% sulfuric acid. Analogously, phthalic anhydride (146) gives the following products anthranilic acid (147), benzimidazol-2-one (150) and some 3,l-benzoxazine-2,4(l//)-dione (isatoic anhydride) (151) in sulfuric acid and benzimidazol-2-one (150) in acetic acid. A recent report" has revealed that Ae Schmidt reaction of phthalic acid (145) in 90-98% sulfuric acid gives anthranilic acid (147) and anthranilazide (149) (major products) by a process thought to involve 3,l-benzoxazine-2,4(l//)-dione (151) as an intermediate. Benzimidazol-2-one (150) is produced in this reaction by a secondary process from anthranilazide (149). Photolysis of (149) also produces (150). 

Coppola, G.M., The chemistry of 2//-3,l-benzoxazine-2,4(l//)-dione (isatoic anhydride). Part 20. Synthesis and Wittig reactions of dimethyl (4-oxo-l,4-dihydro-qurnolrn-2-yl)methanephosphonates, Synthesis. 81, 1988. 

Synthesis of heterocyclic compounds on the basis of isatoic anhydrides (2H-3,1 -benzoxazine-2,4-diones) 01KGS43 5. 

In 1899, Erdmann obtained the same compound in good yield from anthranilic acid and phosgene and suggested the name isatoic anhydride. An alternative synthesis of isatoic anhydride [2//-3,l-benzoxazine-2,4(lH)-dione, subsequently abbreviated as lA] was found by Curtius and Semper from phthalic acid monoazide (5) via o-carboxyphenyl isocyanate. Similar rearrangements were discovered by Bredt and Hor [from potassium phthal-imide (6)] and by Mohr [from phthalimide (7)] leading to IA via a Hoffmann reaction. 

COMPOUNDS BASED ON ISATOIC ANHYDRIDES (2H-3,l-BENZOXAZINE-2,4-DIONES). (REVIEW)... 

Data published after 1979 on the chemical transformations of 2H-3,l-benzoxazine-2,4-diones (isatoic anhydrides), leading to the formation of other heterocyclic compounds, are reviewed, classified, and analyzed. 

H-2,1-Benzoxathiol-3-ylidene) diphenol S,S-dioxide. See Phenol red 2H-3,1-Benzoxazine-2,4(1H)-dione. See Isatoic anhydride Benzoxazole... 

Flosequinan [76568-02-0], vasodilator, antihypertensive, 116. In one method, phosgenation is used to synthesize the benzoxazine-2,4-dione (isatoic anhydride), a key intermediate en route to 116 [87]. Other methods avoiding phosgene have also been reported [88, 89). 

Chloro-2W-3,1 -benzoxazine-2,4(1 W)-dione 5-Chloroisatoic anhydride C8H4CIN03 4743-17-3 197.576 280 dec ... 

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