Total Synthesis of Dendrochrysanene through a Frame Rearrangement

5 years ago

Total Synthesis of Dendrochrysanene through a Frame Rearrangement

Shumpei Isshiki, Juan Okamura, Naoki Katsuki, Takeo Kawabata, Kouji Kuramochi, Kazunori Tsubaki, Daisuke Fukatsu

The first total synthesis of dendrochrysanene (1) was achieved. The key reaction for the construction of dendrochrysanene was an oxidative frame rearrangement reaction from a phenanthrene dimer to a spiro-lactone skeleton, which we serendipitously identified. Owing to the steric hindrance of the substituent on the peri position of the phenanthrene dimer, high-temperature conditions were required for the rearrangement reaction; however, at such temperatures, the substrate decomposed. To address this issue, we added phenylethylamine or benzylamine to the reaction system. We assumed that the amine trapped generated hydrochloric acid and acted as a ligand for iron, helping to maintain an appropriate redox potential. The total synthesis of dendrochrysanene, involving this rearrangement reaction, is an important sequence interlinking phenanthrene derivatives, phenanthrene dimers, and spiro-lactone compounds, which are frequently isolated from plants of Orchidaceae.

Publisher URL: http://dx.doi.org/10.1021/acs.joc.7b02223

DOI: 10.1021/acs.joc.7b02223