Expanding the scope of enzymatic carboligation reactions in flow-mode: production of optically active tertiary alcohols with packed-bed micro-bioreactors
作者:P. P. Giovannini、O. Bortolini、A. Cavazzini、R. Greco、G. Fantin、A. Massi
DOI:10.1039/c4gc00838c
日期:——
Acetylacetoin synthase (AAS) from Bacillus licheniformis has been partially purified and immobilized on a silica support and its activity was tested under batch conditions in the homo-coupling of a set of α-diketones leading to valuable α-hydroxy ketone derivatives displaying a chiral tertiary alcohol functionality at the α-position. Next, the effectiveness of AAS heterogeneous catalysis has been evaluated
Enzymatic diastereo- and enantioselective synthesis of α-alkyl-α,β-dihydroxyketones
作者:Pier Paolo Giovannini、Giancarlo Fantin、Alessandro Massi、Valentina Venturi、Paola Pedrini
DOI:10.1039/c1ob05928a
日期:——
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
α-Diketones as acyl anion equivalents: a non-enzymatic thiamine-promoted route to aldehyde–ketone coupling in PEG400 as recyclable medium
作者:Olga Bortolini、Giancarlo Fantin、Marco Fogagnolo、Pier Paolo Giovannini、Valentina Venturi、Salvatore Pacifico、Alessandro Massi
DOI:10.1016/j.tet.2011.08.056
日期:2011.10
By mimicking the peculiar behavior of thiamine diphosphate-dependent acetylacetoin synthase, it has been demonstrated that thiamine hydrochloride 2a and its simple analogue thiazolium salt 2b are able to activate alpha-diketones as acyl anion equivalents in nucleophilic acylations, such as the homo-coupling of alpha-diketones and the hitherto unreported cross-coupling between a-diketones and alpha-ketoesters. These carboligation reactions were optimized under stoichiometric (2a) and catalytic conditions (2b) by using eco-friendly PEG400 as the reaction medium, thus allowing both solvent and thiazolium salt recycling. (C) 2011 Elsevier Ltd. All rights reserved.
Enzymatic Chemoselective Aldehyde-Ketone Cross-Couplings through the Polarity Reversal of Methylacetoin
作者:Giovanni Bernacchia、Olga Bortolini、Morena De Bastiani、Lindomar Alberto Lerin、Sabrina Loschonsky、Alessandro Massi、Michael Müller、Pier Paolo Giovannini
DOI:10.1002/anie.201502102
日期:2015.6.8
α‐hydroxy ketones through the rare aldehyde–ketone cross‐carboligation reaction. Unprecedented is the use of methylacetoin as the acetyl anion donor in combination with a range of strongly to weakly activated ketones. In some cases, Ao:DCPIP OR produced the desired tertiary alcohols with stereochemistry opposite to that obtained with other ThDP‐dependent enzymes. The combination of methylacetoin as acyl anion