Cu-Catalysed synthesis of benzo[f]indole-2,4,9(3H)-triones by the reaction of 2-amino-1,4-napthoquinones with α-bromocarboxylates

Multicomponent synthesis of 3-(1H-indol-3-yl)-2-phenyl-1H-benzo[f]indole-4,9-dione derivatives

Herein, we report a one-pot greener methodology for the synthesis of 3-(1H-indol-3-yl)-2-phenyl-1H-benzo[f]indole-4,9-dione derivatives by the multicomponent reaction of arylglyoxal monohydrate, 2-amino-1,4-naphthoquinone, and indole in acetonitrile medium under reflux conditions in the presence of 10 mol% sulfamic acid as a catalyst in 20-30 min of reaction time. Three new bonds have formed (2 C-C, 1 C-N) in this methodology. Bioactive moieties such as indole, pyrrole and naphthoquinone are present in our product. This methodology is also applicable in gram-scale synthesis. A wide variety of substrates were tested to find the generality of the methodology and good yield of the products were obtained in a very short reaction time. Along with the operational simplicity of the methodology, purification process of the products is easier by simple recrystallization process. All the synthesized products were characterized by spectroscopic techniques such as FTIR, 1H NMR, 13C NMR, and HRMS.

Copper(I)-Mediated Divergent Synthesis of Pyrroquinone Derivatives and 2-Halo-3-amino-1,4-quinones

A divergent transformation of 2-amino-1,4-quinones for the synthesis of pyrroquinone derivatives and 2-halo-3-amino-1,4-quinones was disclosed. The mechanistic study showed that both the tandem cyclization and halogenation involved a Cu(I)-catalyzed oxidative radical process. This protocol not only constructed a series of novel pyrroquinone derivatives with high atom economy but also provided a new method of halogenation via directed C(sp²)-H functionalization with CuX (X = I, Br, Cl) serving as the X (X = I, Br, Cl) source.

One-pot synthesis of indole-fused nitrogen heterocycles via the direct C(sp2)–H functionalization of naphthoquinones; accessibility for deep red emitting materials

A convenient one-pot, two-step methodology was developed for the transformation of readily available planar naphthoquinone derivatives into structurally complex indole-fused nitrogen heterocycles under aerobic conditions.