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7940158 
Journal Article 
Stereoselective Synthesis of the Tricyclic Core of (-)-Callophycoic Acid A 
Sakama, A; Kameshima, R; Motohashi, Y; Sumida, W; Unno, Y; Yoshida, K; Ogura, A; Takao, KI 
2020 
Yes 
Journal of Organic Chemistry
ISSN: 0022-3263
EISSN: 1520-6904 
85 
5 
3245-3264 
English 
31920083 
WOS:000518875700034 
Two stereocontrolled routes to the tricyclic core of (-)-callophycoic acid A are described. Our synthetic strategy relied on stereoselective allylboration using a new allylboronate reagent to construct the all-carbon quaternary stereocenter in the core, followed by efficient radical cyclization or palladium-catalyzed reductive cyclization to form its multisubstituted cyclohexane ring. The tetrahydrooxepin ring was constructed by intramolecular etheration. This study provides the first method for the stereoselective synthesis of the characteristic tricyclic skeleton of callophycoic acids.