Cinnolines. Part VIII. Methylation of some substituted cinnolines

Abstract

Methylation of 4-hydroxy-3-methylcinnoline gives two products, by alkylation at N-1 and N-2, whereas 4-hydroxy-8-methylcinnoline yields only the anhydro-base formed by alkylation at N-2. Similarly, quaternisation of 3-methylcinnoline with methyl iodide gives the 1- and 2-methiodides, but only the 2-methiodide is obtained from 8-methylcinnoline. The methylations of 4-hydroxy-6-nitrocinnoline, 4-hydroxy-8-nitrocinnoline, and related compounds have been re-examined, and some of the structures assigned to the products in the literature have been revised on the basis of chemical and spectroscopic evidence.