A Novel Conversion of C_<19>-Diterpenoid Alkaloids into Aconane-Type Diterpenes with Eight-Membered Ring System via Skeletal Rearrangement of Corresponding Diazonium Derivatives

概要

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A new and efficient approach toward the conversion of C_<19>-diterpenoid alkaloids into diterpenes with [6+8+5+6] ring system is reported. Treatment of imines 5, 14, and 24 derived from the C_<19>-diterpenoid alkaloids with NaNO_2-NaOAc-HOAc afforded a series of novel rearrangement diterpenes 6-8, 15-19, and 25-27, respectively. The lactone 11 was obtained in 41% yield by treating 5 with NaNO_2-HBr-Br_2. The formation of diazonium intermediate is postulated, which was subsequently subjected to skeletal rearrangement, leading to the enlargement of B ring. All the new compounds were isolated and fully characterized.
公益社団法人日本薬学会の論文
2009-03-01