Acyloxy Derivatives from Extranuclear Halogenoquinoxalines

These quinoxalinylalkyl esters of aUcane- or arenecarboxylic acids are sometimes used as intermediates (see, e.g.. Section 3.4.2). The formation of an analogous quinoxalinylmethyl nitrate is included in this section. Examples follow. 

Ethyl 3-bromomethyl- (270, R = Br) gave ethyl 2-acetoxymethyl-6,7-difluoro-2-quinoxalinecarboxylate 1,4-dioxide (270, R = OAc) (AcOH-AcMe, 20°C, Et3N dropwise, 15 min then substratej, slowly, 20°C, 2h 80%). °  

3-Bis(bromomethyl)-5-nitroquinoxaline (271, R = Br) gave 2,3-bis(acetoxy-methyl)-5-nitroquinoxaline (271, R = OAc) (AcOK, HaO-EtOH, 60°C, 8h 83%) the 5-methoxy analog (66%) was made similarly.  

2-Bromomethyl-3-methylquinoxaline (273) and m-hydroxybenzoic acid (274) gave either 2-(m-hydroxybenzoyloxymethyl)-3-methylquinoxaline (275) [KOH (1 mol), EtOH, reflux, 2h 69%] or 2-(m-carboxyphenoxymethyl)-3-methylquinoxaline (276) [KOH (2 mol), EtOH, 50°C— reflux, 1 h 44%] p-hydroxybenzoic acid reacted similarly but o-hydroxybenzoic acid (salicylic acid) gave only the isomer of product (275) even in the presence of KOH (2 mol). It would seem that the substrate (275) preferred to react at the phenolic anion rather than at the carboxylate anion when both were present 

2-Bromomethyl-6,7-dimethoxy-l-methyl-2(l//)-quinoxalinone reacts with many fatty and other acids (K2CO3, 18-crown-6, MeCN, 80°C, 20 min) to afford analytically useful fluorescent esters.  

---