Dimethyl 2.3-quinoxalinedicarboxylate

Although derivatives of 2,1,3-benzoxadiazole have been used extensively to make quinoxalines (see Section 1.6.7), the corresponding selena and thia systems have been paid scant attention for that purpose. However, 5-chloro-4-nitro-2,l,3-benzoselenadiazole (456) has been used as a convenient source of 4-chloro-3-nitro-1,2-benzenediamine (457) (HCl + HI, 20°C, 2 h 88%), which was then converted into 6-chloro-5-nitro-2,3(l//,4//)-quinoxalinedione (458) (oxalic acid, 2M HCl, reflux, 2.5 h 23%). ° In addition, irradiation of 2,1,3-benzoselenadiazole (460, X = Se) or 2,1,3-benzothiadiazole (460, X = S) with dimethyl acetylenedicarboxy-late afforded, among other products, dimethyl 2,3-quinoxalinedicarboxylate (459)... 

Dimethyl-2,3-quinoxalinedicarboxylic acid (32) gave 6,7-dimethylquinox-alinedicarboxylic anhydride (33) (Ac20, reflux %).401... 

Dimethyl 5,8-diethoxy-2,3-quinoxalinedicarboxylate Dimethyl 2,3-dimethyl-5,6-quinoxalinedicarboxylate Dimethyl 2,3-dimethyl-6,7-quinoxalinedicarboxylate Dimethyl 6,7-dimethyl-2,3-quinoxalinedicarboxylate... 

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