Elucidation of the regio- and chemoselectivity of enzymatic allylic oxidations with Pleurotus sapidus – conversion of selected spirocyclic terpenoids and computational analysis

Abstract

Allylic oxidations of olefins to enones allow the efficient synthesis of value-added products from simple olefinic precursors like terpenes or terpenoids. Biocatalytic variants have a large potential for industrial applications, particularly in the pharmaceutical and food industry. Herein we report efficient biocatalytic allylic oxidations of spirocyclic terpenoids by a lyophilisate of the edible fungus Pleurotus sapidus. This ''mushroom catalysis'' is operationally simple and allows the conversion of various unsaturated spirocyclic terpenoids. A number of new spirocyclic enones have thus been obtained with good regio-and chemoselectivity and chiral separation protocols for enantiomeric mixtures have been developed. The oxidations follow a radical mechanism and the regioselectivity of the reaction is mainly determined by bond-dissociation energies of the available allylic CH-bonds and steric accessibility of the oxidation site.2233

Pleurotus ostreatus as a Biocatalyst to Obtain Bicyclic Hydroxylactones with Three or Four Methyl Groups

“…Biotransformations of the unsaturated compounds described in the literature using fungi of the Pleurotus genus are mainly based on hydroxylation in the allylic position [15][16][17][18]. In our case, this type of reaction was not observed.…”

“…In the current studies, Pleurotus ostreatus strains were used as biocatalysts. These fungi belong to the oyster family, which are, as already mentioned before, known for their ability to hydroxylate terpenoid compounds [15][16][17][18]. Seven strains of Pleurotus ostreatus were tested during the screening biotransformation.…”

“…They are also applicable in biotransformations, where they are mainly used for hydroxylation of natural terpenes and their derivatives. The most frequently observed reaction is the hydroxylation in the allylic position and subsequent oxidation of the alcohol formed [15][16][17][18].…”

Recent Advances in Homogeneous Metal-Catalyzed Aerobic C–H Oxidation of Benzylic Compounds

“…Although good yields and selectivities have been obtained in most cases, stoichiometric amounts of relatively harmful or unsafe oxidizing agents are required. For safety and environmental reasons, molecular oxygen is the oxidant of choice in most oxidative transformations, and an increasing number of reports concerning oxidation of arylmethylene compounds under aerobic conditions can be found in the literature [62][63][64][65][66][67][68][69][70][71][72][73][74][75][76][77][78]. Interestingly, although a theoretically easier catalyst-product separation has boosted research on heterogeneous catalysts (e.g., polymer-or montmorillonite clay-supported catalysts, Pd, Au, or Co nanoparticles) [79][80][81][82][83][84][85][86][87][88][89][90][91][92][93], leaching problems and efficiency or selectivity issues [79,85,86,90,93] have encouraged investigations on the development of new homogeneous catalyst systems.…”

A Macrosphelide as the Unexpected Product of a Pleurotus ostreatus Strain-Mediated Biotransformation of Halolactones Containing the gem-Dimethylcyclohexane Ring. Part 1

“…Car-3-ene was converted to many oxygenated derivatives by a dioxygenase of P. sapidus [17]. The same enzyme was responsible for the allylic oxidation of valencene to nootkatone and oxidation of the unsaturated fatty acid [18]. In a culture of P. flabellatus and P. sajorcaju , transformation of myrcene to myrcenol was observed [19].…”