Formal Total Synthesis of Okadaic Acid via Regiocontrolled Gold(I)-Catalyzed Spiroketalizations
作者:Chao Fang、Yucheng Pang、Craig J. Forsyth
DOI:10.1021/ol101833h
日期:2010.10.15
Both C19 and C34 spiroketal domains of okadaicacid were assembled using gold(I) chloride catalyzed spiroketalizations, and the two resulting fragments were coupled to give the C15−C38 fragment of okadaicacid, a known intermediate for the totalsynthesis of this important natural product.
Three segments A, B and C for okadaicacidsynthesis were coupled with each other in the order of A+(B+C), the key steps of the twice couplings being between sulfone carbanions and aldehydes. After the B+C coupling, the asymmetric center C-27 was generated by a hydride reduction of the corresponding ketone 16 under electronic control. The second coupling was followed to form the C- double bond. Oxidation