Reactions of 2H,5H-imidazo[1,5-b]isoquinoline-1,3-diones with bromine

Abstract

Treatment of 2H,5H-imidazo[1,5-b]isoquinoline-1,3-diones 1 with one molar proportion of bromine in glacial acetic acid gave complex mixtures. The major component of each mixture was the corresponding 1,3-dioxoimidazo[1,5-b]isoquinolinium bromide 4; other constituents shown to be present included the 1,3-dioxo-10-bromoimidazo[1,5-b]isoquinoliniumbromides 5,2H,5H-imidazo[1,5-b]isoquinoline-1,3-diones 3, isocarbostyryl derivatives 9, dihydroisocarbostyryl derivatives 10, and 3-carbamoylisoquinolines 8. Reaction of the 2H,5H-imidazo[1,5-b]isoquinoline-1,3-diones 1 in glacial acetic acid with excess of bromine afforded 1,3-dioxo-10-bromoimidazo[1,5-b]isoquinolinium bromides 5 as principal products. Bromination of compounds 1 in carbon tetrachloride yielded mainly 1,3-dioxo-2H-imidazo[1,5-b] isoquinolinium bromides 12.