2- Methyl-3- quinoxaline oxidation

Phenylimino)methyl]quinoxalme (186) with dimethyl phosphonate gave 2-[a-amlmo-a-(dimethoxyphosphinyl)methyl]quinoxalme (187) (MeONa, MeOH, reflux, several hours >95%) or with diphenylphosphine oxide gave 2-[a-anilino-a-(diphenylphosphinyl)methyl)quinoxaline (188) (MeONa, EtOH, 0°C, 20 min 95%) several analogs likewise. [Pg.350]

Quinoxaline has been prepared by the reaction of glyoxal with o-phenylenediamine, and 2-methylquinoxaline by the reaction of pyruvic aldehyde or isonitrosoacetone with < -phenylenedi-amine. 2,3-Pyrazinedicarboxylic acid has been prepared only by the permanganate oxidation of quinoxaline. 2-Methyl-5,6-pyrazinedicarboxylic acid has been prepared from 2-methyl-quinoxaline in the same way. - ... [Pg.105]

Quinoxalines are, in general, comparatively easy to prepare, and numerous derivatives have been prepared in work designed to produce biologically active materials. Quinoxaline W-oxides continue to be a focal point of study. Their reactions, as well as their pharmacological actions, continue to stimulate many investigations. Thus 2-methyl-quinoxaline (V,(V -dioxides substituted in the 3-position (e.g., with amide,2 amidino,3 hydrazinocarbonyl,4 and ester5 groups) are potent bacteriocides. [Pg.368]

The 1,5-benzodiazepine 40 on irradiation in benzene under oxygen undergoes oxidative ring contraction to 2-benzoyl-3-methyl-quinoxaline.42 Similarly, photolysis of 7-chloro-2-methylamino-5-phenyl-3//-l,4-benzodiazepine-4-oxide (41) in benzene yields the N-benzoylquinoxaline 42. Related ring contractions of diazepines to reduced quinoxalines have also been observed.43... [Pg.378]

Although the 1,3-diphenyl 2-oxo compound 63 is stable to acid hydrolysis, imidazo[4,5-h]quinoxaline itself undergoes very ready hydrolytic ring opening. Hot dilute hydrochloric acid gives 3-aminoquinoxalin-2-one (74), and hot alkali affords 2,3-diaminoquinoxaline (57). Similarly acid treatment of the 2-methyl N-oxides 72 and 73 provides the quinox-aline N-oxides 75 and 76, respectively. ... [Pg.667]

Duque-Montano BE, Gomez-Caro LC, Sanchez-Sanchez M, Monge A, Hemandez-Baltazar E, Rivera G, Torres-Angeles O (2013) S3mthesis and in vitro evaluation of new ethyl and methyl quinoxaline-7-carboxylate 1,4-di-W-oxide against Entamoeba histolytica. Bioorg Med Chem 21 4550-4558. doi 10.1016/j.bmc.2013.05.036... [Pg.111]

Other reactions with their counterparts in the pyridine series are also well known. Thus, 2,3-dimethylpyrazine 1,4-dioxide reacts with acetic anhydride to yield 2,3-bis(acetoxy-methyl)pyrazine (S3) in good yield (72KGS1275). Pyrazine 1-oxide also reacts directly with acetic anhydride to yield 2(ljH)-pyrazinone by way of the intermediate acetate (Scheme 22). The corresponding reaction in the quinoxaline series is not so well defined and at least three products result (Scheme 23) (67YZ942). [Pg.171]

Quinoxaline, 6-hydroxy-applications, 3, 195 tautomerism, 3, 173-174 Quinoxaline, isopropyl-oxidation, 3, 169 Quinoxaline, 2-methyl-bromination, 3, 167-168 oxidation, 3, 169 reactions... [Pg.835]

Substituents in the 2-position generally inhibit 1-oxide formation for example, oxidation of 2-alkoxy- ° and 2-carbethoxy-quinoxalines" furnishes the 4-oxides. Treatment of quinoxaline 2-carboxy-A -methyl-anilide (38) with 1 mole of peracetic acid gives the 4-oxide (39), and oxidation with excess of peracetic acid the 1,4-dioxide (40). ... [Pg.216]

A sulfoxide was obtained by oxidation of 8-[(4-trifluoromethylmercapto-phenyl)methoxy] derivative 358 with 36% H2O2 in AcOH (98MIP7) and by oxidation of l-[2-(4-thiomorfolin-l-yl)acetyl]-7-(3-methoxyphenyl)-A-methyl-A- [3,5-bis(trifluoromethyl)phenyl]ethyl -5-oxo-1,2,3,5-tetrahydro-pyrido[l,2,3-i/ ]quinoxaline-6-carboxamide with 3-chloroperbenzoic acid (01MIP12). A 7-[(4-fluorophenylsulfonyl)methyl] derivative was obtained by oxidation of a 7-[(4-fluorophenylsulfanyl)methyl]perhydropyrido[l,2-u] prazine with 3-chloroperbenzoic acid in CHCI3 (01EUP1074257). [Pg.304]

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]

Dimethylquinoxaline (147) gave 2-ethoxycarbonyl-2-hydroxy -methyl-2,3-dihydro-[l/ ]-pyrrolo[l,2-u]quinoxalin-10-ium bromide (148) (BrCH2CO-C02Et, AcEt, reflux, 3h, then 20°C, 12 h 72%) and thence successively ethyl 4-methylpyrrolo[l,2-fl]quinoxaline-2-carboxylate (149) (EtONa, EtOH, 20°C, 4h 93% note oxidation by loss of H2O), the uncharacterized quaternary salt (150) (as the first step but 6h 50%), and diethyl dipyr-rolo[l,2-fl 2, l -c]quinoxaline-2,ll-dicarboxylate (151) (KOH, H2O, reflux, 1 h 56%). ° " - ... [Pg.119]

Quinoxaline A-oxides have marked biological effects for example, N- 2-hydroxyethyl)-3-methyl-2-quinoxahnecarboxamide 1,4-dioxide (Olaquindox BA-YO-N-OX) is marketed as a growth-promoting feed additive for stock " ... [Pg.225]

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]

Acetyl-3-methylquinoxaline 4-oxide (218, X = 0) gave 2-methyl-3-(l-tosyl-hydrazonoethyl)quinoxaline 1-oxide (218, X = NNHTs) (TSNHNH2, MeOH,... [Pg.298]

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-[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]

Af-Ethylhydrazino)quinoxaline 4-oxide (277, R = Et) and dimethyl acetylene-dicarboxylate gave dimethyl 1-ethyl-l,2-dihydropyridazino[3,4-/ ]quinoxa-line-3,4-dicarboxylate (278, R = Et) (EtOH, reflux, 3 h 77%) the 1-methyl homolog (278, R = Me) (70%) was made similarly. ... [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]

Azido-3-methylquinoxaline 1,4-dioxide (293) underwent thermolytic ring contraction with loss of N2 to give a separable mixture of 2-methyl-3//-benzimidazole-2-carbonitrile 1,3-dioxide (294) and its rearrangement product, 3-methyl-3//-2,l,4-benzoxadiazine-3-carbonitrile 4-oxide (295) (PhH, reflux, 10 min 46% and 41%, respectively) the latter product (295) was also obtained from the benzimidazole (294) (PhH, reflux, 30 min 76%) or from the quinoxaline (293) (PhMe, 90°C, 30 min 94%). ... [Pg.313]

Reaction of commercially available 3-chlorotetronic acid 762, obtained by pyrolysis of methyl 2,4-dichloroacetoacetate at 140 °C in vacuo [235], with o-phenylene-diamine affords, after cyclization-oxidation with AgOAc, the quinoxaline lactone 763 in 69% yield [234] (Scheme 5.83). [Pg.128]

Methyl-3-(l,2,3-trihydroxypropyl)quinoxaline (179) gave 3-methyl-2-quinox-alinecarbaldehyde (180) (NaI04, NaHC03, H20, 20°C, 12 h 73% note preferential oxidation of hydroxylated alkyl substituent) 915 for analogous examples, see Section 4.3.2. [Pg.125]

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