Discovery and properties of a new indigoid structure type based on dimeric cis-indigos

Org Biomol Chem. 2020 Aug 5;18(30):5838-5842. doi: 10.1039/d0ob01368d.

Abstract

Reactions of indigo with quinones in the presence of sodium hydride leads unexpectedly to products containing two indigo subunits; one indigo is featured in a cis configuration and fused via its indole nitrogen atoms to a second indigo at the central C-C bond of the latter. Structural, optical, and redox properties of the new compounds are reported.