新規スピロノルリグナン骨格を有するSequosempervirin A の立体制御合成

抄録

The structure of sequosemperivirin A, isolated from Sequoia sempervirens (Taxodiaceae), was determined to be (4R)-4-(4-hydroxybenzyl)spiro[4,5]dec-1-en-8-ol on the basis of spectroscopic data including its X-ray analysis.
We were able to establish a novel synthetic path to construct a spiro[4.5]decane ring skeleton by using a samarium diiodide-promoted intramolecular Barbier-type reaction of 4-(3-iodopropyl-1-trimethylsilyloxy)-2- oxabicyclo[2.2.2]octan-3-one as the key step. By application of this strategy, we succeeded in a concise stereocontrolled synthesis of (-)-sequosempervirin A starting from the known cyclohexanone derivative in 20 steps in 26.6% overall yield. Based on this asymmetric synthesis, the absolute configuration of the natural compound was revised to (4S)-4-(4-hydroxybenzyl)spiro[4.5]dec-1-en-8-ol.