1-Nitroisoquinolineについて

抄録

1-Nitroisoquinoline (I) is obtained by the application of sodium nitrite to 1-iodoisoquinoline (II) in dimethyl sulfoxide (Chart 1). The ring-carbon at 1-position in I shows nucleophilic activity by the electronic effect of the ring nitrogen and the nitro group, and the nitro group is substituted with various substituents by reaction with nucleophilic reagents (Chart 2), but the ring-carbon at 4-position also becomes a nucleophile active according to the kind of reagents used. For example, when I is heated with sodium phenyl sulfide in benzenethiol, the phenylthio group is introduced into the 4-position of I, with concurrent reduction of the nitro group, to form 1-amino-4-(phenylthio) isoquinoline (X). Benzenethiol is assumed to take part in the reduction of the nitro to amino group, and diphenyl disulfide is obtained as one of the reaction products (Chart 3). Finally, N-oxidation of I was attempted and I was recovered without the formation of 1-nitroisoquinoline 2-oxide (XI). It was considered that this was due to (1) decrease in the basicity of the ring-nitrogen by the electronic effect of the nitro group, and (2) steric interference of the nitro group on the ring nitrogen.