3- Trifluoromethyl-2 -quinoxalinone

A,A-Dibenzyl-2-(ethoxycarbonylmethyl)amino-4-(trifluoromethyl)aniline (27) underwent reductive debenzylation and spontaneous cyclization to 6-trifluoro-methyl-3,4-dihydro-2(17/)-quinoxalinone (28) [Pd(OH)2/C, EtOH, H2 (3 atm), 3 days 97%]. " °... 

Methyl-1,2-benzenediamine (215, R = Me) with the hydrate of 3,3,3-trifluoro-pyruvic acid gave a mixture of isomers (216, R = Me) and (217, R = Me) (dioxane, reflux, 30 min 98%) from which neither appears to have been isolated in a pure state in contrast, 4-nitro-1,2-benzenediamine (215, R = NO2) and the same synthon gave a mixture of 6-nitro- (216, R = NO2) and 7-nitro-3-trifluoromethyl-2(l//)-quinoxalinone (217, R = NO2) (dioxane, reflux, 4 h 95%), from which both isomers were isolable, albeit with... 

Only one procedure in this category emerged from the present survey. Thus treatment of 1,2-benzenediamine (372) with 3,3-bis(trifluoromethyl)-5-oxazolinone (373, R = H) in ethyl acetate containing a trace of acetic acid at room temperature for a short time afforded 2(l//)-quinoxalinone (374, R = H) in 92% yield 3-methyl- (374, R = Me), 3-isopropyl- (374, R = Pr"), 3-phenyl- (374, R = Ph), and 3-benzyl-2(l//)-quinoxalinone (374, R = CH2Ph) were made similarly in 60-80% yield. ... 

Trifluoromethyl-2(l//)-quinoxalinone (164) and ethoxyethylene gave 3-for-mylmethyl-3-trifluoromethyl-3,4-dihydro-2(17/)-quinoxalinone (166), presumably via the tricyclic adduct (165) (MeCN, hv. A, 20°C, 1 h 87%) ... 

Dimethyl-1,2-benzenediamine (384) and 2,2,3-trifluoro-3-trifluoromethyl-oxirane (385) gave 3-trifluoromethyl-2(l//)-quinoxalinone (386) (NaHCC>3, CH2C12-Et20, 23°C, sealed, 12 h 78%) 192 analogs similarly.1001... 

A series of quinoxalinones have been prepared by reaction of o-phenylenediamine with 2-trifluoromethyl-5-oxazolones (17). These intermediates are prepared by reaction of a-amino acids with trifluoroacetic anhydride (Scheme 7). ... 

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