Synthesis of Flavin‐Indole Conjugates with Rigid Diamino Linkers as Cryptochrome Model Compounds

The synthesis of flavin-indole conjugates with a trans-1,4-diaminocyclohexane and 2,6-diaminodecahydronaphthalene linker is reported. Both compounds should serve as artificial model for natural cryptochrome. It assumed that cryptochrome photoreceptor proteins located in the retina show light-dependent quantum effect which enables migratory birds to perceive Earth's magnetic field thus used navigation. were prepared by stepwise reductive aminations indole carbaldehyde flavin-substituted acetaldehyde appropriate diamine linkers. hitherto unknown was four steps from 2,6-dihydroxynaphthalene achiral (meso) ax,ax,trans-diastereoisomer. configuration this key intermediate well synthetic precursors has been established series X-ray single crystal analyses.