2- / -Bromophenyl quinoxaline

This category of primary synthesis is extremely rare in the quinoxaline series, although a few examples have been reported in recent literature. Thus a mixture of neat 1,2-benzenediamine (331) and an excess of p-bromobenzaldehyde heated at 350°C for 5 min afforded (with aerial oxidation ) 2,3-bis(p-bromophenyl) quinoxaline (332) in 50% yield " " and analogs were made similarly but usually in poor to mediocre yield after separation from byproducts." " In addition, an... 

Note Both direct and indirect alkanelyses are illustrated in these examples. 2,3-Bis(p-bromophenyl)quinoxaline (91) with phenylacetylene (2 equiv) gave 2,3-bis[p-(phenylethynyl)phenyl]quinoxaline (92) (PhsP, Cul, EtsN, AcN Me2, 20°C, A, 15 min then (Ph3P)2PdCl2 i, SOX, 10 h 20%). ... 

Quinoxaline /V-oxides undergo rearrangements when UV-irradiated. 2,3-Diphenylquinoxaline 1-oxide (224) was originally thought to rearrange to the oxazirino[2,3-a]quinoxaline (225).225 However, subsequently the product was found to be 2,4-diphenyl-3,l,5-benz-oxadiazepine (226).226 This reassignment was supported by NMR spectroscopy, and oxadiazepine formation on irradiation of 2,3-bis(4-bromophenyl)quinoxaline 1-oxide was confirmed by X-ray crystallography.227... 

The synthesis of the precursors of 232, 233, i.e., the macrocycles 219, 220 is based on the 3-(3-bromophenyl)quinoxalin-2-one 225b. At the first stage, the methoxycarbonylpyrrolidine moiety was introduced through an oxygen atom of the carbamoyl group to form 226 (Scheme 5.53). Further, during the interaction of... 

C22H1 iiNg, 2,3-Bisbenzimidazol-2-yl-quinoxaline, 46B, 263 C22H16N2O, 2,4-Diphenyl-2,3-benzodiazocin-1(2H)-one, 42B, 211 C22H1sBrNOa, E,E-1-Acetyl-3-(1 -p-bromophenyl)-3 -ethoxycarbonyl-allylidene)-2-0X0-indoline, 45B, 283 C22H19N3O5, 4-Ethoxycarbonyl-5-hydroxy-1-phenyl-3-(a-phthalimidoeth-yDpyrazole, 46B, 263... 

A special method for the synthesis of pyrrolo[l,2-a]quinoxalines using the PA4 synthon has not been developed. However, during the production of pyrrolo-1,4-benzodiazepines by the insertion of carbon monoxide into 2-[N-R-N-(2-bromophenyl)aminomethyl]pyrrolidines 187 in the presence of catalytic amounts of Pd(OAc)2 and PPhs pyrrolo[l,2-a]quinoxalines 190 were found together with other products formed as a result of the migration of, for example, an acyl group from the aniline nitrogen atom to the pyrrolidine nitrogen atom (Scheme 3.56) (Mory et al. 1984). 

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