109958-04-5Relevant articles and documents
Asymmetric Allylation Catalyzed by Chiral Phosphoric Acids: Stereoselective Synthesis of Tertiary Alcohols and a Reagent-Based Switch in Stereopreference
Lazzarotto, Mattia,Hartmann, Peter,Pletz, Jakob,Belaj, Ferdinand,Kroutil, Wolfgang,Payer, Stefan E.,Fuchs, Michael
, p. 3138 - 3143 (2021)
The substrate scope of the asymmetric allylation with zinc organyls catalyzed by 3,3-bis(2,4,6-triisopropylphenyl)-1,1-binaphthyl-2,2-diyl hydrogenphosphate (TRIP) has been extended to non-cyclic ester organozinc reagents and ketones. Tertiary chiral alcohols are obtained with ee's up to 94% and two stereogenic centers can be created. Compared to the previous lactone reagent the stereopreference switches almost completely, proving the fact that the nature of the organometallic compound is of immense importance for the asymmetry of the product. (Figure presented.).
Mechanistic Studies of the TRIP-Catalyzed Allylation with Organozinc Reagents
Hartmann, Peter E.,Lazzarotto, Mattia,Pletz, Jakob,Tanda, Stefan,Neu, Philipp,Goessler, Walter,Kroutil, Wolfgang,Boese, A. Daniel,Fuchs, Michael
, p. 9672 - 9679 (2020/09/03)
3,3-Bis(2,4,6-triisopropylphenyl)-1,1-binaphthyl-2,2-diyl hydrogenphosphate (TRIP) catalyzes the asymmetric allylation of aldehydes with organozinc compounds, leading to highly valuable structural motifs, like precursors to lignan natural products. Our previously reported mechanistic proposal relies on two reaction intermediates and requires further investigation to really understand the mode of action and the origins of stereoselectivity. Detailed ab initio calculations, supported by experimental data, render a substantially different mode of action to the allyl boronate congener. Instead of a Br?nsted acid-based catalytic activation, the chiral phosphate acts as a counterion for the Lewis acidic zinc ion, which provides the activation of the aldehyde.
Enzymatic synthesis of optically active lactones via asymmetric bioreduction using ene-reductases from the old yellow enzyme family
Turrini, Nikolaus G.,Hall, Mélanie,Faber, Kurt
, p. 1861 - 1871 (2015/06/02)
In contrast to the widely studied asymmetric bioreduction of α,β-unsaturated carboxylic acid esters catalyzed by ene-reductases, the reaction applied to lactones remains unexplored. A broad set of ene-reductases was found to reduce various α-, β- and γ-substituted α,β-unsaturated butyrolactones to yield the corresponding saturated non-racemic lactones. Substitution patterns greatly influenced activities and stereoselectivities and lactone products were obtained in moderate to excellent yields; importantly, enzyme-based stereocontrol allowed access to both enantiomers in up to >99% ee. Chiral recognition of a distant γ-center led to kinetic resolution with remarkable enantioselectivities (E values up to 49). An unprecedented case of dynamic kinetic resolution was observed with 3-methyl-5-phenylfuran-2(5H)-one, whereby spontaneous racemization of the substrate furnished the product in up to 73% conversion and >99% ee and 96% de.
