Cinnolinones alkylation

Alkylation of 3-ethoxycarbonyl-4( 1//)-cinnolinones by alkyl iodides or dialkyl sulfates with potassium carbonate in DMF gives a mixture of the 3-ethoxycarbonyl-l-alkyl-4(l//)-cinnolinones along with the anhydro bases formed by alkylation of N-2. The latter compounds undergo hydrolysis and decarboxylation in acid <89CPB93). 

Tautomeric cinnolinones usually undergo A -alkylation to afford regular N-alkylcinnolinones, zwitteiionic Al-alkylcinnoliniumolates, or a mixture of both 0-alkylation to afford alkoxycinnolines is rare but not unknown. These possibilities are illustrated in the following classified examples. 

Note Unlike alkylation, acylation of a tautomeric cinnolinone usually affords an acyloxycinnoline rather than an A-acylated cinnolinone. 

Note The formation of these ethers by primary synthesis Chapter 1), by alcoholysis or phenolysis of halogenocinnolines (Section 3.2), and by alkylation of tautomeric cinnolinones (Section 4.1.2.1) has been covered already. Other routes appear to be unrepresented. 

Note A few such products have been made by primary synthesis (see Chapter 1) but most, by alkylation of tautomeric cinnolinones (see Section 4.1.2.1). Minor routes are exemplified here. 

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