3 生理活性な鎖状減成テルペノイドの新しい位置及び立体選択的合成

概要

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Biologically active linear degraded terpenoids, a diol component (1a) of the pheromonal secretion of the queen butterfly and ω-quinoid hexenoic acid (2a), a final metabolite of ubiquinones were synthesized from easily accessible isoprenoids (7) by a new regio- and stereo-selective method in which facile functionalizations of the isopropylidene terminus of isoprenoids and a novel anionic [2,3]-sigmatropic rearrangement accomponied by sulfur extrusion are involved. By the method the degraded β-farnesene (4) was also synthesized. The synthetic sequence is featured by two stages. At first the acetic acid moiety was introduced as the substituent on sulfur into the isoprenoid skeleton to give regiospecifically the terminal allylic sulfides (9) by the following methods, one involves addition of the sulfenyl chloride (6) derived from methyl thioglycolate to isoprenoids (7) followed by mild dehydrochlorination and the other involves treatment of (7) with SO_2Cl_2 providing the allylic chlorides (10) which was then treated with methyl thioglycolate in the presence of base. Secondly treatment of (9) with strong base such as t-BuOK or NaH in DMSO resulted in an unique one-pot desulfurizative [2,3]-sigmatropic rearrangement to transfer stereoselectively the acetic acid moiety onto the terminal allylic position of the isoprenoid skeleton yielding the sulfur-free ester (13).
天然有機化合物討論会の論文
1980-09-10