Tered and washed with dichloromethane (three ten mL). The filtrate was concentrated beneath reduced stress,

Tered and washed with dichloromethane (three ten mL). The filtrate was concentrated beneath reduced stress, as well as the Ammonium glycyrrhizinate web reaction crude purified by column chromatography purification working with an eluent gradient 5:1 to 3:1 hexane:EtOAc, isolating acetate (2S,4R)-3a (142 mg, 48 isolated yield) and alcohol (2R,4S)-2a (115 mg, 46 isolated yield), each in enantiopure kind. four. Conclusions A common methodology has been proposed for the synthesis of racemic trans-flavan4-ols bearing various substitution patterns in the aromatic ring at the C-2 position. The five-step chemical route involved three main methods or reaction sequences: (i) the aldol condensation between two -hydroxyacetophenone and various benzaldehydes bearing either electron-withdrawing or electron-donor atoms or groups, followed by an intramolecular Michael-type addition in an acid medium; (ii) the chemical Fucosterol Metabolic Enzyme/Protease reduction inside the flavanones, which led to the corresponding racemic cis-flavan-4-ols with total selectivity and extremely high yields; and lastly, (iii) the configuration inversion from the C-4 position by a Mitsunobu inversion reaction and subsequent chemical hydrolysis in standard circumstances enables the preferential formation from the alcohol trans-isomers soon after optimization in the reaction conditions in the Mitsunobu reaction with regards to employed nucleophile and alkyl diazocarboxylate. Having a series of ten racemic trans-flavan-4-ols on hand, their classical kinetic resolutions had been performed, selecting trans-flavan-4-ol as a benchmark substrate for enzyme screening and reaction situations optimization, locating lipase AK from Pseudomonas fluorescens because the more selective biocatalyst, and vinyl acetate acting as both an sufficient acyl donor and solvent. The (2R,4S)-alcohols and (2S,4R)-acetates were obtained, in all cases, with excellent selectivities (E 200), obtaining distinct conversion values depending on the kind and place in the substitution in the phenyl ring situated in the C-2 position, the para-substituted derivatives getting transformed swiftly by AK lipase from PseudomonasCatalysts 2021, 11,17 offluorescens (490 conversion) in comparison with the meta- (470 ) and, especially, the ortho-substituted ones (336 ).Supplementary Supplies: The following are out there on line at https://www.mdpi.com/article/ 10.3390/catal11111296/s1. Table S1. HPLC conditions for the chiral analyses of trans-flavan-4-ols 2a-j and their corresponding acetates 3a-j. Next, the chromatograms of trans-flavan-4-ols 2a-j and trans-flavan-4-ol acetates 3a-j in racemic and optically active kind can be discovered. Author Contributions: Conceptualization, H.R.-S. and V.G.-F.; investigation (experimental design and style and development of analytical methods), M.S and I.S.-M.; writing–original draft preparation, V.G.-F.; writing–review and editing, M.S., I.S.-M., H.R.-S. and V.G.-F. All authors have study and agreed towards the published version on the manuscript. Funding: Monetary assistance in the Spanish Ministry of Science, Innovation and Universities (PID2019-109253RB-I00) is gratefully acknowledged. Data Availability Statement: The data presented in this study are openly out there in the Repository from the University of Oviedo (https://digibuo.uniovi.es/dspace/). Conflicts of Interest: The authors declare no conflict of interest.
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