“…Monooxygenated terpenoids are relevant target compounds for the synthesis of active pharmaceutical ingredients (APIs), fragrances and nutritional supplements . For instance, ketoisophorone (2,6,6‐trimethylcyclohex‐2‐ene‐1,4‐dione, KIP, 3 ), is one of the key intermediates to access useful building blocks for the synthesis of carotenoids and α‐tocopherol (vitamin E), as shown in Scheme . For instance, the biocatalytic conversion of KIP to the chiral intermediate (4 R ,6 R )‐4‐hydroxy‐2,2,6‐trimethylcyclohexanone ((4 R ,6 R )‐actinol, 4 ), which is an important precursor of several carotenoids, has been recently demonstrated in a one‐pot system employing an engineered Candida macedoniensis old yellow enzyme (CmOYE) and Corynebacterium aquaticum (6 R )‐levodione reductase .…”