Methyl 2-amino-4-bromobenzoate

Cyclocondensation of 2-chloronicotinic acid with 2-amino-5-iodobenzoic acid and methyl 2-amino-4-bromobenzoate in boiling EtOH in the presence of cone. HCl for 18 h gave the 2-iodo and 3-bromo derivatives of 11-0X0-1 l/f-pyrido[2,l-6]quinazoline-6-carboxylic acid (98MIP1, 98MIP2, 99USP5908840, 99USP5914327). 

Figure 11.10 Continuous-flow nitration of methyl 2-amino-4-bromobenzoate.

Catalytic cyclodehydrogenation of 5-amino-2-ethylthiophenol affords 6-aminobenzo[6]thiophene.239,241 6-Acetamido-2,3-di-bromo-,77 6-acetamido-2-bromo-3-methyl-,102 6-acetamido-3-bromo-2-methyl-,102 and 6-acetamido-3-bromobenzo[f>]thiophene107 may be obtained from the corresponding 6-acetyl compound by means of the Schmidt reaction. In some cases the 6-acetamido compound is accompanied by a smaller amount of the amine sulfate.102,107 6-Aminobenzo[6]thiophene may be converted into 6-chloro- or 6-cyanobenzo[6]thiophene by means of the Sandmeyer reaction.241... 

The reactions of amidines or guanidines with a-functionalized carbonyl compounds continue to be utilized for the synthesis of imidazoles. Thus, the mixed anhydride of acetic and chloroacetic acids reacts with symmetrical diarylguanidines to give l-aryl-2-arylaminoimidazolin-4-ones, and there is competitive formation of imidazoles and pyrimidines in the reaction of benzamidine with 3-bromobenzo-4-pyrones (18). Imidazoles are minor products, but are favored in nonpolar solvents. The use of a-dicarbonyl compounds with guanidine gives 2-amino-4-hydroxy-4-methyl-4//-imid-azoles, which give excellent yields of 2-aminoimidazoles on catalytic hydrogenation. " ... 

Loughhead (90JOC2445) coupled 5-amino-2,2-dimethyl-7-methoxy-chromene 244 with 2-bromobenzoic acid, and the resultant product 245 was cyclized with TFAA. The de-A-methylacronycine 210 was then converted to acronycine 208 by methylation under phase-transfer conditions (Scheme 40). The same approach has been used by Elomri et al. to prepare 6-demethoxyacronycine 246 which was found to be more potent than acronycine 208 in some biological assays (92H799). 

By hydrolysis of RA-VII (166), one D-alanine, two molecules of L-alanine, A-methyl-4-methoxy-L-phenylalanine, and A-methyltyrosine dimer having an ether linkage were obtained. The isolate was assumed to be a cyclic hexapeptide consisting of three alanine and three tyrosine molecules. From these findings, the structure of RA-VII was assumed to be a bicyclic hexapeptide having an ether linkage. However, it was difficult to decide the sequence of amino acids and the configuration stereochemically. Finally, X-ray analysis was applied to the p-bromobenzoate of RA-V (164). 

A soln. of methyl 2-amino-5-bromobenzoate in 1,2-dichlorethane added dropwise during 20-30 min. to a refluxing soln. of l-bromoprop-2-yl isocyanate in the same solvent, refluxed 5 hrs., evaporated in vacuo, the residue dissolved in dioxane, boiling water added, treated slowly during 25-35 min. at reflux temp, and pH 4.5-7.5 with a soln. of piperidine in dioxane, and refluxing continued 15 min. -> 7-bromo-3-methyl-5-oxo-2,3-dihydro-5H-[l,3]oxazolo[2,3-b]quinazoline. Y 78-82%. F. e., bases, solvents, and intermediates s. K.-D. Kampe, Synthesis 1976, 469. 

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