Preparation of Nontautomeric Quinoxalinones

Nearly all such quinoxalinones have been made either by primary synthesis (see Chapter 1) or by N-alkylation of tautomeric quinoxalinones (see Section 4.1.2.2). However, several recently used minor routes are illustrated by the following examples. 

3-Methyl-2(17/)-quinoxalmone (215) gave l-benzenesulfonyl-3-methyl-2(17/)-quinoxalinone (216) (PhS02Cl, K2CO3, AcMe, reflux 3 h 90% analogs likewise). 

2-Quinoxalinecarbonitrile (217) gave l-ethyl-2(l/f)-quinoxalinone (218) (EtMgBr, Et20, THE, reflux, 3 h 16% after chromatographic separation from three other products homologs likewise, also in poor yield).  

2-Benzylquinoxaline 1,4-dioxide (219) rearranged into l-benzyl-2,3(l//,4/l)-quinoxalinedione (220) hv, MeOH, until no substrate by tic 21%) analogs 

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