For the complete structure elucidation of an endogenous sperm-activating and -attracting factor isolated from eggs of the ascidian Ascidia sydneiensis (Assydn-SAAF), its two possible diastereomers with respect to C-25 were synthesized. Starting from ergosterol, the characteristic steroid backbone was constructed by using an intramolecular pinacol coupling reaction and stereoselective reduction of a hydroxy ketone as key steps, and the side chain was introduced by Julia–Kocienski olefination. Comparison of the NMR data of the two diastereomers with those of the natural product led to the elucidation of the absolute configuration as 25S; thus the complete structure was determined and the first synthesis of Assydn-SAAF was achieved.

中文翻译：

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从海鞘亚述中提取精子激活和吸引因子的合成及完整结构的测定

为了阐明分离自海生孢子虫（Ascidia sydneiensis）（Assydn -SAAF）卵的内源性精子激活和吸引因子的完整结构，合成了其相对于C-25的两种可能的非对映异构体。从麦角固醇开始，通过分子内频哪醇偶联反应和羟基酮的立体选择性还原为关键步骤，构建了特征性类固醇骨架，并通过Julia-Kocienski烯烃引入了侧链。的两种非对映同那些导致的绝对构型为25的阐明天然产物的NMR数据的比较小号; 因此，确定了完整的结构，并实现了Assydn -SAAF的首次合成。