Manganese complex catalyst for valencene oxidation: The first use of metalloporphyrins for the selective production of nootkatone

The polymerization of carvacrol catalyzed by Mn-porphyrins: obtaining the desired product guided by the choice of solvent, oxidant, and catalyst

“…Possibly, the interaction between the catalyst, solvent, and dissolved molecular oxygen could lead to the formation of active species (entries 2, 3, 9, 10, 16, and 17 in Table 1; systems with catalysts and no added oxidants); however, as the oxygen solubility in the medium must be low, 43 the substrate conversion is not complete (but it is higher than expected – up to 55%). Normally, oxygen-mediated oxidation occurs under high pressures, as observed by Melo et al 21 for MnP-mediated valencene oxidation by O 2 at 25 °C.…”

“…Metalloporphyrins and some other metal complexes have been used as catalysts for the oxidation of various natural products. 2,10,21–24 Regarding carvacrol's oxidation, few Mn( iii )-porphyrins were used as catalysts in the presence of H 2 O 2 or t -BuOOH, with thymoquinone being the main product. 10,12,14 Also, other studies investigated carvacrol oxidation with Oxone® employing metalloporphyrins or phthalocyanines as oxidants.…”

“…This catalytic behavior was verified in other studies, in which an iodoarene was used in reactions in the presence of atmospheric O 2 . 21,61 Nascimento et al 61 reported high yields for allylic products in the cyclohexene oxidation by PhIO, while Melo et al 21 showed that the combination of PhIO and O 2 increased the yield for the allylic product derived from valencene, both justified by the ability of PhIO to act as a radical chain initiator. Also, Georgiev et al 62 demonstrated that PhI(OAc) 2 acts as a radical initiator for the methyl methacrylate's and other monomers’ polymerization.…”

Currently Applied Extraction Processes for Secondary Metabolites from Lippia turbinata and Turnera diffusa and Future Perspectives

“…3CL pro , ACE-2, spike glycoprotein, and RdRp [107]. Valencene, the chemical responsible for the fresh odor of oranges, is a sesquiterpene that is easily obtained from citrus fruits and is an inexpensive raw material that can be oxidized into high-value products such as nootkatone (which is another important sesquiterpenoid aroma component of the grapefruit) [108,109]. It is widely used in the flavor and fragrance industries.…”

Advances on (+)-nootkatone microbial biosynthesis and its related enzymes

“…Hong et al found that hydrogen peroxide and amphiphilic molybdate ions could be used to catalyze (+)-valencene to synthetize (+)-nootkatone (Hong et al, 2016 ). It was also found that (+)-valencene could be oxidated by metalloporphyrins to produce (+)-nootkatone for the first time (de Melo et al, 2021 ). In contrast, the biocatalytic transformation method is not limited by the raw materials (Zhang et al, 2020 ).…”