2-Chloro-3- quinoxaline oxidation

Chloroquinoxalin-2(1 W)-one 4-oxide has been selectively hydrogenated to 6-chloro-quinoxalin-2(l/f)-one, using sulfided and non-sulfided catalysts, with the catalyst of choice being sulfided platinum. [Pg.225]

Only one procedure has been reported recently within this category. Thus 7-chloro-l-methyl-5-phenyl-2,3-dihydro-lH-benzodiazepin-2-one 4-oxide (437) with dimethyl acetylenedicarboxylate in methylene chloride at 20° C for 3 days gave a separable mixmre of the primary tricyclic adduct, dimethyl lO-chloro-6-oxo-llb-phenyl-5,6,7, 1 lb-tetrahydroisoxazolo[2,3-t/] [ l,4]benzodiazepine-1,2-dicarboxylate (438), and its rearrangement product, 6-chloro-4-(2-methoxalyl-2-methoxycarbonyl-l-phenylvinyl)-l-methyl-3,4-dihydro-2(lT0-quinoxalinone (439) each product afforded 6-chloro-l-methyl-2(l//)-quinoxalinone (440) on refluxing in ethanol (see also Section 1.7.13). However, the final quinoxaline (440) was best obtained in 75% yield) by simply heating the initial substrate (437) and dimethyl... [Pg.59]

Chloro-3-methylquinoxaline 4-oxide gave 3-chloro-2-quinoxalinecarbalde-hyde 1-oxide (172) (SeOi, PhH, reflux, h 72%) dioxane may be used as solvent for such oxidations yielding, for example, 3-amino-2-quinoxaline-carbaldehyde ethyl acetate may also be so used. [Pg.124]

Chloro-2-quinoxalinamine (210) and pyridine gave pyrido[l, 2 l,2]imi-dazo[4,5-fc]quinoxaline (211) (Mc2NCHO, 100°C, 48 h 49% note aerial oxidation). Several 3-substituted analogs were made similarly using appropriate pyridine derivatives. ... [Pg.171]

A( -p-Bromobenzylidene-A-meihylhydrazino)-6-chloroquinoxaline 4-oxide (289) gave dimethyl 4-(A( -p-bromobenzylidene-A(-methylhydrazino)-8-chloro-3a//-isoxazolo[2,3-fl]quinoxaline-2,3-dicarboxylate (290) [Me02CC = CC02Me (1 mol), dioxane, reflux, 2 h >95%]." ... [Pg.238]

Likewise, 6-chloro-2-piperidinoquinoxaline 4-oxide (291) gave dimethyl 8-chloro-4-piperidino-3 a//-isoxazolo [2,3 -a] quinoxaline-2,3 -dicarboxylate (292)... [Pg.238]

Chloro-2-(Af-methylhydrazino)quinoxaline 4-oxide (295) gave ethyl 7-chloro-1 -methyl- //-[ 1,3,4]oxadiazmo[5,6-Z7]qumoxaline-3-carboxylate (296) (Et02-CCOCl, pyridine, CHCI3, 5°C —> reflux, 2 h 81% mechanism discussed). ... [Pg.240]

This minor but important route enables a quinoxalinamine to be converted into the corresponding nitroquinoxaline by oxidation of a derived dimethylsulfimido-quinoxaline. Thus 3-chloro-2-quinoxalinamme (24) was converted into 2-chloro-3-dimethylsulfimidoquinoxahne (25) (68-88% see Section 6.3.2.4), which underwent initial oxidation to a green solution of 2-chloro-3-nitrosoquinoxaline (26) (m-ClC6H4C03H, CH2CI2, 5°C, 40 min then Me2SJ 0°C, 10 min) and thence further oxidation to 2-chloro-3-nitroquinoxaline (27) (O3J, 0°C, until colorless 20-... [Pg.260]

Chloro-2-(A -methylhydrazino)quinoxaline 4-oxide (227, R = H) gave 2- N -acetyl-A -methylhydrazino)-6-chloroquinoxaline 4-oxide (227, R = Ac) (AC2O, pyridine, dioxane, reflux, 30 min >95%) or 6-chloro-2-(A-methyl-A -trifluoroacetylhydrazino)quinoxaline 4-oxide [CHCI3, (F3CC0)20i drop-wise, <5°C then reflux, 1 h 63%]." ... [Pg.301]

Chloro-2-(A(-methyIhydrazino)quinoxaline 4-oxide gave 6-chloro-2-[A( -(fur-2-ylmethylene)-A(-methyIhydrazino]- (232, X = O) (2-furaldehyde, dioxane, reflux, 1 h >95%)" or 6-chloro-2-[A(-methyl-A( -(thien-2-ylmethylene) hydrazinojquinoxahne 4-oxide (232, X = S) (2-thiophenecarbaldehyde, dioxane, reflux, 1 h 91%). ... [Pg.302]

Cbloro-2-(Al-methylhydrazino)quinoxaline (244) gave 6-chloro-2-[l-methyl-4-phenyl(tbiocarbazido)]quinoxaline (245) (PhNCS, CHCI3, reflux, 2 h 87%) " the corresponding 4-oxide (86%) was made similarly but in... [Pg.304]

Chloro-2-hydrazinoquinoxaline 4-oxide and acetylacetone gave 6-chloro-2-(3,5-dimethylpyrazol-l-yl)quinoxaline 4-oxide (249) (EtOH, reflux, 2 h 68%) analogs likewise. ... [Pg.305]

Chloro-2-[l,4-dimethyl(thiosemicarbazido)]quinoxaline 4-oxide (250) with dimethyl acetylenedicarboxylate gave 6-chloro-2-[A-(5-methoxycarbonyl-methylene-3-methyl-4-oxo-2-thioxoimidazolidin-l-yl)-A-methylammo]quinoxa-line 4-oxide (251) (EtOH, reflux, 5 h 54%) a homolog likewise." ... [Pg.306]

In a similar way, 6-chloro-2-(Al-methylhydrazino)quinoxaline 4-oxide gave... [Pg.310]

Chloro-2-[A -methyl-Af -(thien-2-ylmethylene)hydrazino]quinoxaline 4-oxide (288, R = H) with 2-chloroacrylonitrile gave 8-chloro-4-hydroxy-l-methyl-... [Pg.311]

Dichloroquinoxaline 1-oxide (118, R = C1) gave 6-chloro-2-(/V-methylhy-drazmo)quinoxaline 1-oxide (118, R = NMeNH2) (MeHNNH2, CHCI3, reflux, 1 h 87%) 489... [Pg.155]

Several recent general papers on the properties of quinoxaline N-oxides have reported studies on the crystal structures of quinoxaline 1,4-dioxide,380 its 2,3-dimethyl derivative,380 ethyl 7-chloro-3-methyl-2-quinoxalinecarboxylate 1,4-dioxide,40 and N-(2-hydroxyethyl)-3-methyl-2-quinoxalinecarboxamide 1,4-dioxide 931 the NMR spectral data of quinoxaline 1,4-dioxide for comparison with those of related dioxides 348 the NMR data for biologically active quinoxalinecarboxamide dioxides 381 thermochemical data for several quinoxaline dioxides 183 and polaro-graphic or cyclic voltammetric data for 2,3-disubstituted quinoxaline dioxides.239 894... [Pg.230]

Chloro-2-(A-methylhydrazino)quinoxaline 4-oxide and dimethyl acetylenedi-carboxylate gave 6-chloro-2- /V -( 1,2-dimethoxycarbonylethylidene)-./V-methylhydrazino]quinoxaline 4-oxide (237) (EtOH, C6Hi2, reflux, 3 h 44%).463... [Pg.303]

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