Abnormal reactions of 2‐methoxy‐4,9‐dimethyl‐1‐nitroacridine with selenous acid and selenium(IV) oxide. Synthesis of 1H‐selenopheno[2,3,4‐k,l]acridine‐1‐one: A new seleno‐containing ring system

Abstract

Unusual course of the reaction was revealed on the oxidation of functionally substituted acridine containing the activated methyl groups by well-known oxidants, such as selenous acid and selenium(IV) oxide. Treatment of 2-methoxy-4,9-dimethyl-1-nitroacridine (5) with an excess of H 2 SeO 3 in boiling ethanol gave a mixture of the normal reaction products, 2-methoxy-4-methyl-1-nitro-9-formylacridine (11) (isolated yield 29%) and 2-methoxy-4-methyl-1-nitroacridine-9-carboxylic acid (12) (36%), together with an abnormal product, 3-methoxy-5-methyl-1H-selenopheno[2,3,4-k,l]acridine-1-one (13) (21%), which is the first example of a new seleno-containing ring system. With the use of SeO 2 the yield of selenolactone 13 was much lower.