Regio‐ and Enantio‐selective Chemo‐enzymatic C−H‐Lactonization of Decanoic Acid to ( S )‐δ‐Decalactone

The conversion of saturated fatty acids to high value chiral hydroxy‐acids and lactones poses a number of synthetic challenges: the activation of unreactive C−H bonds and the need for regio‐ and stereoselectivity. Here the first example of a wild‐type cytochrome P450 monooxygenase (CYP116B46 from Tepidiphilus thermophilus) capable of enantio‐ and regioselective C5 hydroxylation of decanoic acid  1 to ( S )‐5‐hydroxydecanoic acid  2 is reported. Subsequent lactonization yields ( S )‐δ‐decalactone  3 , a high value fragrance compound, with greater than 90 % ee . Docking studies provide a rationale for the high regio‐ and enantioselectivity of the reaction.