Hydrolysis, Alcoholysis, or Phenolysis of Extranuclear Halogenoquinoxalines

Direct hydrolysis of (monohalogenoalkyl)quinoxalines can be difficult but indirect routes are available. Alcoholysis and phenolysis are usually straightforward processes. The following examples illustrate both direct and indirect procedures. 

6-Bromomethyl-2,3-dimethoxy-7-methylquinoxahne (257) gave 6-hydroxy-methyl-7-methyl-2,3(l//,47/)-quinoxalonedione (258) (IM HCl, reflux, 12 h 49% note concomitant hydrolysis of the methoxy groups).  

Crude 5-dibromomethylquinoxaline (259) (prepared by bromination of 5-methylquinoxaline) gave 5-quinoxalinecarbaldehyde (261) via the hydrate (260) (CaCOs, H20-Et0H, reflux, 3h 71%)/  

3-Bis(bromomethyl)quinoxaline 1,4-dioxide (262) gave 2,3-bis(acetoxy-methyl)quinoxaline 1,4-dioxide (263) (AgOAc, AcOH, 45°C, dark, 17 h 40%) and thence 2,3-bis(hydroxymethyl)quinoxaline 1,4-dioxide (264) (2M HCl 90°C, 5 min -40%). ° =  

6-Bromomethyl-2,3-dimethoxy-7-methylquinoxaline (265) underwent a classical Sommelet reaction and incidental hydrolysis of the methoxy groups to give 7-methyl-2,3-dioxo-l,2,3,4-tetrahydro-6-quinoxalinecarbaldehyde (266) (hexamethylenetetramine, CHCI3, 20°C reflux, 30 min solid from evapora- 

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