6-Chloro-3,3-dimethyl-3,4-dihydro-2 quinoxalinone

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... 

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. " ... 

Chloro-3- [(1 -ethoxycarbonyl-1 -methylethyl)amino] -4-nitrobenzene (61) gave 6-chloro-3,3-dimethyl-3,4-dihydro-2(l //)-quinoxalinone (62) (TiCl3, AcONa, HeO-MeOH, 20°C, 2.5 h >95%).1042... 

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