7.8- Dimethyl-6 -quinoxalinone

Alkylation of pyrazinones and quinoxalinones may be carried out under a variety of conditions and it is usually observed that while O-alkylation may occur under conditions of kinetic control, to yield the corresponding alkoxypyrazines or alkoxyquinoxalines, under thermodynamic control the A-alkylated products are formed. Alkylation using trialkyl-oxonium fluoroborate results in exclusive O-alkylation, and silylation under a variety of conditions (75MI21400) yields specifically the O-silylated products. Alkylation with methyl iodide or dimethyl sulfate invariably leads to A-methylation. [Pg.173]

In contrast, the reaction of dimethyl acetylenedicarboxylate with the benzodiazepinone 4-oxide 21 gives the quinoxalinone 24 by way of the isolable intermediates 22 and 23.249... [Pg.416]

Dimethyl-1,2-benzenediamine with phenylglyoxylic acid (PhCOC02H) gave 6,7-dimethyl-3-phenyl-2(17/)-quinoxalinone (212, R = Ph) (EtOH, reflux. [Pg.30]

The same substrate (218) and ethyl ethoxalylacetate (Et02CC0CH2C02Et) gave 3-ethoxycarbonylmethyl-2(l//)-quinoxalinone (221, R = H) (EtOH, reflux, 3 h 80% ° likewise but 15 min 64%) the homologous substrate, 3,6-dimetyl-l,2-benzenediamine, and the same synthon gave 3-ethoxycarbonyl-methyl-5,8-dimethyl-2(l//)-quinoxalinone (221, R = Me) (AcOH, reflux, briefly 61%). ... [Pg.32]

Benzenediamine (228) and diethyl dibromomalonate (229) gave ethyl 3-oxo-3,4-dihydro-2-quinoxalinecarboxylate (230) (MeOH, 20°C, 24 h 40%)." The same substrate (228) with ethyl a-bromoisobutyrate gave 3,3-dimethyl-3,4-dihydro-2(17i)-qumoxalinone (231) (Me2NCHO, NEtPr j, 110°C, 7 h 76%) or with methyl 2-bromo-2-phenylacetate gave 3-phenyl-3,4-dihydro-2(l//)-quinoxalinone (232) (KI, K2CO2, AcMe, reflux, 12 h then oily product, MeONa, PhH, reflux, 7 h 89%). ... [Pg.33]

Dimethyl-1,4-benzoquinone (328) and ethylenediamine (329) gave 7,8-dimethyl-6(4//)-quinoxalinone (330) (EtOH-CH2Cl2, 20°C, light exclusion 35% the required oxidation was probably provided by an excess of the quinone). ... [Pg.44]

Recent examples of this synthesis are of two types. The first involves condensation of the activated phenol, 2-amino-4,6-dinitrophenol (346a) with 2-dimethyl-amino-3,3-dimethyl-3//-azirine (346b) (in MeCN, 0°C- 20°C, A, 24 h) to afford a separable mixture of four products, one of which was 2-dimethylamino-3,3-dimethyl-5,7-dinitro-3,4-dihydroquinoxaline (346c) ( 20% yield) and another its hydrolysis product, 3,3-dimethyl-5,7-dinitro-3,4-dihydro-2(l//)-quinoxalinone (346d) ( 8%) the mechanism of such condensations has been discussed. ... [Pg.47]

The unlikely transformation of a pyrimidine into a quinoxaline has, indeed, been reported. Thus 4,5-dimethyl-1,2-benzenediamine (402) and alloxan (403, R = H) under acidic conditions gave 6,7-dimethyl-3-ureidocarbonyl-2(17/)-quinoxalinone (404, R = H) ( 30% see original for details) A(-methylalloxan (403, R = Me) likewise gave 6,7-dimethyl-3-(A(-methylureido)carbonyl-2(17/)-quinoxalinone (404, R = Me) in 50% yield.Such condensations gave improved yields under solid-state conditions. [Pg.54]

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]

An analogous substrate, dimethyl 10-chloro-7-methyl-6-oxo-l lb-phenyl-5,6,7,1 lb-tetrahydroisoxazolo[2,3-d][l,4]benzodiazepine-l,2-dicarboxylate (566), gave not 567 but 6-chloro-l-methyl-2(l/7)-quinoxalinone (EtOH, reflux, 30 h -40%). ... [Pg.77]

As in the preceding subsection, l,2-bis(benzenesulfonylimino)-4,5-dimethyl-benzene (598) and 2-phenylthiazolo[3,2-fl]quinolinium-l-olate (599) in dichloromethane at 20°C during 15 min afforded l,4-bis(benzenesulfonyl)-6,7-dimethyl-3-phenyl-3-(quinolin-2-ylthio)-3,4-dihydro-2(l//)-quinoxalinone (600) in almost quantitative yield. " ... [Pg.82]

Ethoxalylmethyl-l-methyl-2(177)-quinoxalinone (118) underwent deacylation to give l,3-dimethyl-2(177)-quinoxalinone (119) (80% H2NNH2-H20, reflux,... [Pg.114]

Ethoxycarbonylmethyl-2(l//)-quinoxalinone (62) gave 3-methoxycarbonyl-methylene-l,4-dimethyl-3,4-dihydro-2(l/ )-quinoxalinone (63) (CH2N2,... [Pg.199]

Dimethyl-2(l//)-quinoxalinone (64) gave 6,7-dimethyl-2-trimethylsiloxy-quinoxaline (65) (excess MesSiNHSiMea, trace (NH4)2S04, reflux, 20 h crude solid) and thence 6,7-dimethyl-l-(2,3,5-tri-(9-benzoyl-p-D-ribofurano-syl)-2(l//)-quinoxalinone (66) (l-(9-acetyl-2,3,5-tri-(9-benzoyl-p-D-ribofura-nose, BFs EtjO, CH2CI2, 20°C, 3 h 36% overall). ... [Pg.199]

Methyl-2(17/)-quinoxalinone (109) and 2-methylacrylonitrile (110) gave the photoadduct, l,2a-dimethyl-3-oxo-2,2a,3,4-tetrahydro-l//-azeto[ 1,2-u]quinoxa-line-l-carbonitrile (111) (CH2CI2, MeOH, hv, N2, <15 h >95%) also analogs using significantly electron-deficient olefines. [Pg.205]

Methoxy-5-nitro-3-phenylquinoxaline gave only 6-methoxy-5-nitro-3-phenyl-quinoxaline 1-oxide (232) (AcOH, 30% H2O2, 80°C, 3 h 81%) 1,3-dimethyl-2(17/)-quinoxalinone 4-oxide (233) was made similarly but in only... [Pg.226]

Chloro-2,2-dimethyl-3-oxo-1,2,3,4-tetrahydro-1 -quinoxalinecarbonyl chloride (89) gave 6-chloro-4-(3,5-dimethylpiperazin-l-yl)carbonyl-3,3-dimethyl-3,4-dihydro-2(177)-quinoxalinone (90) [substrate, EtPr N, CH2CI2 HN(CH2-CHMe)2NHi, 0°C 20°C, 17 h 54%] analogs likewise. " ... [Pg.334]

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