An enzymatic strategy for the preparation of optically pure α-alkyl-α,β-dihydroxyketones is reported. Homo- and cross-coupling reactions of α-diketones catalyzed by acetylacetoin synthase (AAS) produce a set of α-alkyl-α-hydroxy-β-diketones (30-60%, ee 67-90%), which in turn are reduced regio-, diastereo-, and enantioselectively to the corresponding chiral α-alkyl-α,β- dihydroxyketones (60-70%, ee >95%) using acetylacetoin reductase (AAR) as catalyst. Both enzymes are obtained from Bacillus licheniformis and used in a crude form. The relative syn stereochemistry of the enantiopure α,β-dihydroxy products is assigned by NOE experiments, whereas their absolute configuration is determined by conversion of the selected 3,4-dihydroxy-3-methyl-pentan-2-one to the natural product (+)-citreodiol. © The Royal Society of Chemistry 2011.
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Data di pubblicazione: | 2011 | |
Titolo: | Enzymatic diastereo- and enantioselective synthesis of alpha-alkyl-alpha,beta-dihydroxyketones | |
Autori: | Giovannini, Pier Paolo; Fantin, Giancarlo; Massi, Alessandro; Venturi, Valentina; Pedrini, Paola | |
Rivista: | ORGANIC & BIOMOLECULAR CHEMISTRY | |
Abstract: | An enzymatic strategy for the preparation of optically pure α-alkyl-α,β-dihydroxyketones is reported. Homo- and cross-coupling reactions of α-diketones catalyzed by acetylacetoin synthase (AAS) produce a set of α-alkyl-α-hydroxy-β-diketones (30-60%, ee 67-90%), which in turn are reduced regio-, diastereo-, and enantioselectively to the corresponding chiral α-alkyl-α,β- dihydroxyketones (60-70%, ee >95%) using acetylacetoin reductase (AAR) as catalyst. Both enzymes are obtained from Bacillus licheniformis and used in a crude form. The relative syn stereochemistry of the enantiopure α,β-dihydroxy products is assigned by NOE experiments, whereas their absolute configuration is determined by conversion of the selected 3,4-dihydroxy-3-methyl-pentan-2-one to the natural product (+)-citreodiol. © The Royal Society of Chemistry 2011. | |
Digital Object Identifier (DOI): | 10.1039/c1ob05928a | |
Handle: | http://hdl.handle.net/11392/1523520 | |
Appare nelle tipologie: | 03.1 Articolo su rivista |