Synthesis of Bridged Indigos and Their Thermoisomerization and Photoisomerization Behaviors

• DOI: 10.1021/acs.joc.1c01726
• Publication Date: 2021-11-24T17:04:41Z
• Authors: Junya Kanda; Naoki Egami; Takahiro Sasamori; Ayumi Imayoshi; Takashi Hosoya; Kazunori Tsubaki
• Keywords: Racemization; Chirality

Bridged indigos were synthesized by bridging the two nitrogen atoms in indigo structure with a carbon chain, and their properties carefully examined. These bridged have intrinsic planar chirality, enantiomers separated using chiral high-performance liquid chromatography. When subjected to thermo- photoisomerization, corresponding (Z)-indigo was not observed at all, racemization observed. This phenomenon is caused low activation energy of inversion due 1.5 bond order double skeleton large difference between ground states (E)-indigo (Z)-indigo.