本篇論文利用C2對稱的雙烯雙醇化合物2作為起始物，經由交叉置換反應、環丙烷化反應、Sharpless不對稱α-羥基化反應和環閉合置換反應合成天然物brevipolide H的鏡像異構物 (ent-1)。其中天然物的中心結構，是以硫ylide對α,β-不飽和酮5進行環丙烷化反應，形成符合天然物之鏡像異構物的立體位向。此立體結構經由X-ray單晶繞射確定。此外，藉由γ醇上保護基的改變 (乙基甲醚和縮丙酮)，可以發展出相反的環丙烷位向；之後再依序與4-甲基肉桂酸進行酯化、與3-丁烯酸進行Mitsunobu反應，建構天然物brevipolide H之鏡像異構物 (ent-1) 右端的4-甲基肉桂酯及左端的5,6-二氫-2-吡喃酮結構。 ;We utilized the C2 symmetric diene-diol 2 as the starting material, and the skeleton of ent-brevipolide H (ent-1) was prepared by the sequence of cross metathesis, cyclopropanation, Sharpless asymmetric α-hydroxylation and ring-closing-metathesis. The anti-addition of the sulfur ylide to the α,β-unsaturated enone 5 was be developed to generate the key cyclopropane moiety, whose stereochemistry was lated confirmrd by X-ray crystallography. The substrates with different hydroxyl protecting groups, i.e. ethoxymethyl ether and acetonide, lead to the different stereo-assignment of the cyclopropane. The first total synthesis of ent-brevipolide H (ent-1) was achieved after the linkage of 4-methoxycinnamic acid to an ester, the formation of 5,6-dihydro-2-pyrone and deprotection.
