FL-120B

Six new kinamycin antibiotics have been isolated from the culture filtrate of Streptomyces chattanoogensis. The structures of six related components were determined employing 1D and 2D NMR spectroscopy and mass spectrometry. These structures represent the first reported epoxide kinamycin (2, 3) and propionyl derivative of kinamycin (5), and new isobutyryl derivatives of kinamycin (1, 4, 6).

Turn up the heat: An asymmetric total synthesis of the epoxykinamycin FL-120B' is reported. The synthesis establishes a route to epoxide-containing diazobenzofluorenes which could potentially serve as monomers to the dimeric lomaiviticins. Key steps include Sharpless asymmetric epoxidation, Stille coupling, and intramolecular Friedel-Crafts acylation of atropisomeric carboxylic acids at elevated temperatures to construct the FL-120B' core structure.

Photo-Friedel-Crafts acylation of a naphthoquinone was attempted in an effort to access a diazobenzofluorenone en route to the epoxykinamycin natural product FL-120B'. Photoirradiation of the naphthoquinone substrate which resulted in the unexpected formation of a tetracyclic naphthofuran via a decarbonylative photocyclization process is described.