Title: Synthetic studies toward aromatic polyketide antibiotics

Speaker: Prof. Takuya Kumamoto
                Department of Synthetic Organic Chemistry, Graduate School of Biomedical and Health sciences,
                Hiroshima University, Japan

Abstract:
We are developing methodology for cyclization reaction for total synthesis of bioactive natural products containing polycyclic aromatic rings. Recent achievement of our research is asymmetric total synthesis of antitumor antibiotic angucycline brasiliquinones. The key reaction of this total synthesis is oxidative cyclization of naphthohydroquinone-silyl enol ether hybrids for the formation of B ring. This reaction was at first examined for the construction of tetracyclic core of angucycline, however, formation of pentacyclic acetal was coincidentally observed. Multiple transformation of the corresponding silyl enol ether under Larock oxidation condition afforded target compound brasiliquinones.¹⁾

Another target of total synthesis is teretifolione B, monomer unit of conocurvone, anti-HIV-1 active trimeric chromenoquinone isolated from Australian plant. Optically active chromene, obtained by enzymatic resolution was converted to the pyranobenzyne, which was subjected to Diels-Alder reaction with oxygenated furan afforded teretifolione B.²⁾

References
(1) Miyake, H.; Nakajima, R.; Kumamoto, T. J. Org. Chem. 2022, 87, 12491.
(2) Kumamoto, T. Chem. Rec. 2025, e202500265.

Host: Prof. Fujie Tanaka (Tanaka Unit)