1.3- Oxazine-2,6-dione-4-carboxylic acid

H-l,2-Oxazine-3-carboxylic acid, 5,6-dihydro-synthesis, 1, 484 Oxazine-4,6-dione, 2-methylene-synthesis, 3, 1031... 

An X-ray crystal structural determination revealed that the 8-carboxyl group of cij-4fl,8-H-l,3,4,4a,7,8-hexahydropyrido[l,2-c][l,3]oxazine-8-carboxylic acid is in a pseudoaxial position (81JA7573). The crystal structure of 4-phenyl-2- 4-[4-(2-pyrimidinyl)piperazin-l-yl]butyl -2,3,5,6,7,8-hexahydro-l//-pyrido[l,2-c][l,3]oxazine-l,3-dione was determined by an X-ray investigation (95ZK899). 

When a nonproteinogenic unsaturated amino acid was subjected to the Sharpless asymmetric epoxidation, 49 was formed (87TL3605). It is known that AAs are converted with phosgene into A-carboxy-a-amino acid anhydride (NCA) derivatives. Unexpectedly, A-protected dehydroaspartic acid gave l,3-oxazine-2,6-dione-4-carboxylic acid under such conditions (88CL1473). 

Alicyclic 2-isocyanato-l-carboxylic acids 214 synthesized from alicyclic trimethylsilyl 2-amino-l-carboxylates 213 were cyclized to the unstable 2-thioxoperhydro-l,3-oxazin-4-ones, which isomerize to the thermodynamically more stable perhydro-l,3-thiazine-2,4-diones 215 (cm, X = CH2 — CH2, CH = CH trans, X = CH2-CH2) (74MI2). 

Depending upon the reaction conditions, 2-ethoxy-3,4,5,6-tetrahydropy-ridine and isopropylidene 2-acetylmalonate afforded either perhydropy-rido[2,l-h][l,3]oxazine-2,4-dione (162) or hexahydropyrido[2,l-b][l,3]ox-azine-3-carboxylic acid (163) (86MI1). Reaction of 2-methoxy-3,4,5, 6-tetrahydropyridine with diketene without a solvent gave a mixture of 4H-quinazolin-4-one (164) and hexahydropyrido[2,l-h][l,3]oxazin-4-one (165) [75H(3)927]. 

Cyclization of methyl 4-(c/s-3,5-H-2-oxomorpholin-5-yl)butyrate in boiling toluene provided c/s-4,9a-H-4-phenylperhydropyrido[2,l-c][l,4]ox-azine-3,6-dione [95H(41)1931], Heating l,4-oxazin-2-one 163 afforded [l,4]oxazino[4,3-a]quinoline-4,6-dione 164 (94IZV299, 94JFC119). The reaction of carboxylic acid 165 with l.l -carbonyldiimidazole in the presence of 4-methylmorpholine afforded pyrido[2,l-c][l,4]oxazin-4-one (61)... 

Epimers of 3-methylperhydropyrido[2,l-c][l,4]oxazine (189) were prepared by oxymercuration-demercuration of l-(3-propenyl)-2-hydroxy-methylpiperidine (188) [93JCR(M)1620, 93JCR(S)251]. Asymmetric bro-molactonization of optically active tetrahydroisoquinoline-3-carboxylic acid 190 gave a 5 1 mixture of l,3,4,6,ll,lla-hexahydro[l,4]oxazino[4,3-6]-isoquinoline-l,4-diones (191) and (192) (77CL1109 79T2345). 

Chloro-l,7-dimethylpyridazino[3,4-carboxylic acid (132). This reaction is reversed in acetic anhydride. 

Thiophene analogs 47 of isatoic anhydride have been synthesized and their chemical reactivity towards nucleophiles have been studied <03TL10051>. Unlike the reaction of isatoic anhydride with a nucleophile wherein both 2-ureidobenzoic acid and 2-carbamoylbenzoic acid are obtained, 6- and 7-arylthieno[3,2-r/][l,3]oxazine-2,4-diones have been shown to give only the ureidothiophen carboxylic acid 48. 

CAS 118-48-9 EINECS/ELINCS 204-255-0 Synonyms Anthranilic acid N-carboxylic acid anhydride 1H-Benzo[D][1,3] oxazine-2,4-dione 2H-3,1-Benzoxazine-2,4(1H)-dione lA Isatoic acid anhydride... 

Many ring-fused imidazole derivatives have been synthesized by various methods. Domino Michael addition retro-ene reaction of 2-alkoxyiminoimidazolidines and acetylene carboxylates provided a synthesis of 2,3-dihydroimidazo[l,2-a]pyrimidin-5-(l//)-ones <05T5303>. A single step synthesis of 3,5-dialkyl-9-nitroimidazo[l,2-c]quinazolin-2(3//)-ones from simple carbonyl compounds, primary amines or amino acid methyl esters and 2-azido-5-nitrobenzonitrile has been published <05TL5778>. Diels-Alder reaction of azadienes and benzimidazole-4,7-diones afforded imidazo[4,5-g ]quinoline-4,9-dione derivatives <05EJ01903>. Reaction between isocyanides and dialkyl acetylenedicarboxylates in the presence of 4,5-diphenyl-l,3-dihydro-2//-imidazol-2-one provided a one-pot synthesis of 5//-imidazo[2,l-ft][l,3]oxazine derivatives <05T2645>. Microwave irradiation was employed in the synthesis of 1-ary 1-3-acetyl-1,4,5,6-... 

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