Bioinspired Synthesis of Juglorubin from Juglomycin C.

In this paper, the synthesis of juglorubin, a natural red dye, from juglomycin C, a plausible biogenetic precursor, is reported. Sequential intermolecular and intramolecular Michael additions of juglomycin C, oxidation, and skeletal transformation proceeded in phosphate buffer to afford an undehydrated derivative of juglorubin. Subsequent dehydration of the secondary alcohol afforded juglorubin. The one-pot synthesis of juglorubin from juglomycin C was also achieved. The photophysical properties of synthetic juglorubin and its derivatives were evaluated.