Abstract
| - A concise and highly enantioselective route has been developed for the synthesis of angucyclinone-typenatural products. Utilizing this strategy, total syntheses of five natural products YM-181741, (+)-ochromycinone, (+)-rubiginone B2, (−)-tetrangomycin, and MM-47755 have been accomplished in 22%,23%, 19%, 18%, and 12% overall yields, respectively. Our approach for the synthesis of these naturalproducts having the benz[a]anthraquinone skeleton is based on a sequential intramolecular enynemetathesis, intermolecular Diels−Alder reaction (DAR), and aromatization. The intramolecular enynemetathesis reaction was employed for the synthesis of enantiopure 1,3-dienes in excellent yields.Furthermore, the synthesis of YM-181741 as well as structurally similar angucyclinones such as (+)-ochromycinone and (+)-rubiginone B2 was achieved via asymmetric enolate alkylation of an oxazolidinonein excellent de. The related angucyclinones (−)-tetrangomycin and MM-47755, bearing a labile tertiaryalcohol, were synthesized via Sharpless asymmetric epoxidation of a known allylic alcohol followed byopening the epoxide with Red-Al. The introduction of oxygen functionality at C-1 in all these naturalproducts was accomplished by photooxygenation under a positive pressure of oxygen.
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