Quinoline alkaloids. Part 26. Pseudobases from the reaction of furoquinolinones with methyl iodide. A new route to 3-(3-methyl-2-oxobutyl)quinolin-2(1H)-ones

Abstract

Reaction of 2-isopropyl-9-methylfuro[2,3-b]quinolin-4(9H)-ones (5) with methyl iodide gave salts believed to be pseudobase hydriodides (7), which were converted with base into 4-methoxy-1-methyl-3-(3-methyl-2-oxobutyl)quinolin-2(1H)-ones (6); the analogous pseudobase derivative (12) from the furoquinoline alkaloid skimmianine gives the furoquinolin-4-one isoskimmianine on further reaction with methyl iodide. The mechanisms of these reactions and of the acid-catalysed rearrangement of furoquinolinones (5) are discussed.