作者:Nha Huu Vo、Barry B. Snider
DOI:10.1021/jo00097a053
日期:1994.9
(-)-Silphiperfol-6-ene (10) and (-)-methyl cantabradienate (11) have been prepared in seven steps from (R)-3-methyl-1-cyclopentenecarboxaldehyde in 13 and 9% overall yield, respectively. Addition of isopentenylmagnesium bromide to imine 22 afforded 65% of aldehyde 14. Oxidation provided acid 15, which was converted to ketene 20, which underwent an intramolecular [2 + 2] cycloaddition to afford cyclobutanone 13. Mn(III)-based oxidative fragmentation-cyclization of ethynyl cyclobutanol 25 provided an efficient route to the key methylenecyclopentanone 12. Addition of methyllithium and Birch reduction completed the synthesis of (-)-silphiperfol-6-ene 10. Formation of dienyl triflate 29 and palladium-catalyzed carbonylation concluded the first synthesis of (-)methyl cantabradienate (11).
(-)-Silphiperfol-6-ene (10) 和 (-)-甲基cantabradienate (11) 已经通过从(R)-3-甲基-1-环戊烯羧酸仿开始的七步反应制备而成,总产率分别为13%和9%。将异戊烯基溴化镁加成到亚胺22中,获得了65%的醛14。氧化提供了酸15,将其转化为酮烯20,随后酮烯20通过分子内[2 + 2]环加成反应生成环丁酮13。以Mn(III)为基础的氧化断裂环化反应处理乙烯基环丁醇25,为制备关键的甲基环戊酮12提供了一条高效途径。甲基锂的加成和Birch还原完成了(-)-silphiperfol-6-ene 10的合成。二烯基三氟乙酸酯29的形成以及钯催化的羰基化反应,标志着(-)-甲基cantabradienate (11) 的首次合成。