An efficient and stereoselective syntheses of all the possible stereoisomers of coronafacic acid (CFA) has been developed. The stereochemistries of C3a and C7a were controlled in a diastereoselective Diels‐Alder type cycloaddition using a chiral auxiliary. CFA and 6‐epi‐CFA were synthesized by hydrogenation of a common intermediate. During the synthesis of 6‐epi‐CFA, we established that its cis‐fused configuration is important for the introduction of C4‐C5 double bond by dehydration. This report is the first practical synthesis of both 6‐epi‐CFA, and its enantiomer.

中文翻译：

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冠状面酸所有可能立体异构体的立体选择性合成

已经开发出一种有效且立体选择性合成所有可能的冠发酸（CFA）立体异构体的方法。C3a 和 C7a 的立体化学通过使用手性助剂的非对映选择性 Diels-Alder 型环加成进行控制。CFA 和 6- epi -CFA 通过共同中间体的氢化合成。在 6- epi -CFA的合成过程中，我们确定其顺式稠合构型对于通过脱水引入 C4-C5 双键非常重要。该报告是 6- epi -CFA 及其对映体的首次实际合成。