Chiral carveol and dihydrocarveol are important additives in the flavor industry and building blocks in the synthesis of natural products. Despite the remarkable progress in asymmetric catalysis, convenient access to all possible stereoisomers of carveol and dihydrocarveol remains a challenge. Here, we present the stereodivergent synthesis of carveol and dihydrocarveol through ketoreductases/ene‐reductases catalyzed asymmetric reduction. By directly asymmetric reduction of (R)‐ and (S)‐carvone using ketoreductases, which have Prelog or anti‐Prelog stereopreference, all four possible stereoisomers of carveol with medium to high diastereomeric excesses (up to >99 %) were first observed. Then four stereoisomers of dihydrocarvone were prepared through ene‐reductases catalyzed diastereoselective synthesis. Asymmetric reduction of obtained dihydrocarvone isomers by ketoreductases further provide access to all eight stereoisomeric dihydrocarveol with up to 95 % de values. In addition, the absolute configurations of dihydrocarveol stereoisomers were determined by using modified Mosher's method.

中文翻译：

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酮还原酶/烯还原酶催化的不对称还原立体异构合成香芹酚和二氢香芹醇

手性香芹酚和二氢香芹酚是香料工业中的重要添加剂，是天然产物合成的基础。尽管在不对称催化方面取得了显着进展，但方便地获得香芹酚和二氢香芹酚的所有可能的立体异构体仍然是一个挑战。在这里，我们介绍了通过酮还原酶/烯还原酶催化的不对称还原立体合成香芹酚和二氢香芹醇。通过（R）和（S的直接不对称还原）使用酮还原酶的香芹酮，具有Prelog或anti-Prelog立体偏好，首先观察到了中度至高度非对映异构体过量（高达> 99％）的香芹酚的所有四种可能的立体异构体。然后通过烯还原酶催化的非对映选择性合成制备了二氢香芹酮的四种立体异构体。酮还原酶使获得的二氢香芹酮异构体不对称还原进一步提供了高达85％de值的所有八种立体异构体二氢香芹酚的获取途径。另外，通过使用改进的Mosher方法确定了二氢香蒲醇立体异构体的绝对构型。