Synthesis and structures of benzo[cd]furo[2,3-f]indol-4(5H)-one derivatives

Abstract

A procedure was developed for the synthesis of derivatives of the new heterocyclic system, benzo[cd]furo[2,3 f]indole, based on the cyclodehydration of 6 acylmethyloxy 1 alkyl benzo[cd]indol 2(1H) ones. Either 7 or 8 aryl derivatives of benzo[cd]furo[2,3 f]indol 4(5H) ones can be prepared depending on the reaction conditions. The molecular and crystal structures of 7 and 8 phenylbenzo[cd]furo[2,3 f]indol 4(5H) ones were established by X ray diffraction.

Near Infrared Polyene Radical‐Cation Derived from 7,8‐Dihydrobenzo[c,d]Furo[2,3‐f]Indole: Synthesis, Spectra and Nature of Electron Transitions

“…Polymethine dye 2 (Pm) and quaternary salt 1 were described previously. While working with salt 1 , we observed that when its solution exposed to air, in addition to the intrinsic absorption band of 514 nm, a low‐intensity band of 835 nm appeared.…”

“…Also, other heterocycles with branched own π‐electron system providing the NIR absorption of the polymethine dyes or di‐ hetero‐substituted polyenes, including the residues based on benzo[c,d]indole and its derivatives. So, we earlier have elaborated the methods of synthesis polynuclear heterocyclic system containing 7,8‐dihydrobenzo[ cd ]furo [2,3– f ] indole residue; such terminal groups lead the corresponding polymethine dyes to absorb in NIR spectral region.…”

“…The benzo[c,d]indole is known as an applicable terminal group with the large so‐called “effective length” which enables the near ‐ infrared absorption of the linear molecules with conjugated π‐electronic system, including the polymethine dyes and polyenes. Recently, such compounds have become popular in the development of composites for solar cells, because of their capability to convert light energy into electricity.…”