3-Phenyl-3,4-dihydro-2 -quinoxalinone

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%). ... 

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... 

Ethyl 10-chloro-7-methyl-6-oxo-l lb-phenyl-5,6,7,1 lb-tetrahydroisoxazolo[2, 3- /][l,4]benzodiazepine-l-carboxylate (563) gave a separable mixture of 6-chloro-4-(2-ethoxycarbonyl-2-formyl-l-phenylvinyl)-l-methyl-3,4-dihy-dro-2(17/)-quinoxalinone (564), 4-(2-benzoyl-2-ethoxycarbonylvinyl)-6-chloro-1-methyl-3,4-dihydro-2(l//)-quinoxalinone (565), and 6-chloro-l-methyl-3,4-dihydro-2(l//)-quinoxalinone (567) (EtOH, reflux, 21 h 2%, 8%, and 20%, respectively, after separation structures 564 and 565 were... 

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. " ... 

Amino-5,7-dimethoxy-3-phenyl-2(17/)-quinoxalinone (127) gave 6-methoxy-3-oxo-2-phenyl-3,4-dihydro-5,8-quinoxalinequinone (128) (NaI04, H2SO4, MeOH, H2O, 20°C, 3 min 87%). ... 

Amino-3-phenyl-3,4-dihydro-2(177)-quinoxalinone (181) and triphosgene gave 4-phenyl-47/-imidazo[l,5,4-< e]quinoxaline-2,5(l//, 6//)-dione (182) (EtsN, THF, 20°C, N2, until substrate gone by tic 65%) analogs Ukewise. ... 

Amino-3-phenyl-3,4-dihydro-2(l//)-quinoxalinone (194) gave 5-phenyl-2,3-dihydro-17/, 5//-pyrazino[l,2,3-tie]quinoxaline-2,3,6(77/)-trione (195) [(COCl)2,... 

This category is represented in the facile reaction of o-phenylenediamine (408) with 4-benzoyl-5-phenyl-2,3-dihydro-2,3-thiophenedione (409) (in toluene at 20°C for 30 min) to afford 3-(a-benzoyl-p-mercaptostyryl)-2(l//)-quinoxalinone (410) in 98% yield 744 also in the complicated reaction of 3-methyl-2,2,4-trinitro-2,5-dihydrothiophene 1,1-dioxide (411) with 2 equiv of ethyl 4-aminobenzoate (412) (in acetonitrile but no further details) to give ethyl 2-(p-ethoxycarbonylphenyl)-3-(l-methyl-2-nitrovinyl)-6-quinoxalinecarboxylate (413) in 51% yield.831 Several... 

Acetyl-3-phenyl-3,4-dihydro-2(l/7)-quinoxalinone (191) gave 7-acetyl-3-phe-nyl-2(17/)-quinoxalinone (192) (H202, NaOH, H20, reflux, 90 min 84%).885... 

Hydroxy-3-oxo-3,4-dihydro-2-quinoxalinecarbonitrile 4-Hydroxy-3-oxo-3,4-dihydro-2-quinoxalinecarbonitrile 1-oxide 4-Hydroxy-3-oxo-3,4-dihydro-2-quinoxalinecarboxylic acid 1 -Hydroxy-3-phenyl-2( l/f)-quinoxalinone... 

---