2889-31-8Relevant articles and documents
Pyruvate Aldolases Catalyze Cross-Aldol Reactions between Ketones: Highly Selective Access to Multi-Functionalized Tertiary Alcohols
De Berardinis, Véronique,Gefflaut, Thierry,Gourbeyre, Léa,Guérard-Hélaine, Christine,Hélaine, Virgil,Laurent, Victor,Lemaire, Marielle,Nauton, Lionel,Salanoubat, Marcel,Tra?kia, Mounir,Uzel, Alexandre
, p. 2538 - 2543 (2020)
Tertiary alcohols are widely represented in nature and among bioactive molecules. Their importance is attested by the continuous efforts to meet the challenge of their stereoselective synthesis. In this context, we propose an enzymatic approach, involving class II pyruvate aldolases. These enzymes are shown to catalyze selective cross-aldol reactions between pyruvic acid or derivatives as nucleophiles and a series of ketones as electrophiles. This catalytic activity is exemplified by the highly stereoselective preparation of seven branched ketols with good yields. One of them was readily converted into a constrained 4-hydroxyproline analogue in a multienzymatic one-pot one-step process.
FLAVIN-MEDIATED PHOTOLYSIS OF MYCOSPORINES
Bernillon, Jacques,Parussini, Ermis,Letoublon, Robert,Favre-Bonvin, Jean,Arpin, Noel
, p. 81 - 84 (1990)
Under aerobic conditions and in the presence of flavins, light causes the photolysis of mycosporine glutamine into aminocyclohexenone and 2-hydroxy glutaric acid.This photolysis, which is temperature dependent, is also observed when other photosensitizers which are carriers of singlet oxygen replace flavins.This photodestruction also occurs with mycosporine amino alcohols but at reduced rate and probably by another mechanism.
Metal-catalyzed reductive deamination of glutamic acid to bio-based dimethyl glutarate and methylamines
De Schouwer, Free,Cuypers, Thomas,Claes, Laurens,De Vos, Dirk E.
, p. 1866 - 1876 (2017/06/09)
Glutamic acid is a promising renewable platform molecule which is abundantly available in biomass waste streams; it is also efficiently manufactured by fermentation. Here we report the reductive deamination of glutamic acid to bio-based dimethyl glutarate and methylamines. In order to recycle nitrogen in an industrially relevant co-product, glutamic acid was modified to N,N-dimethylglutamic acid by a mild reductive alkylation with Pd/C. Subsequently, selective C-N hydrogenolysis in methanol resulted in dimethyl glutarate and trimethylamine. A wide screening of transition metals (Pt, Pd, Rh and Ru) immobilized on various supports showed that the highest yields of dimethyl glutarate were obtained with Pt/TiO2. An FTIR study and kinetic experiments on metal-loaded and unloaded supports demonstrate that the interplay between the metal and the moderate acidity of the support results in the excellent C-N hydrogenolysis activity and selectivity. Finally, reaction parameter optimization resulted in 81% yield of dimethyl glutarate with 1 wt% Pt/TiO2 at 225 °C, 30 bar H2 after 8 h.
Hydrothermal conversion of macroalgae-derived alginate to lactic acid catalyzed by metal oxides
Jeon, Wonjin,Ban, Chunghyeon,Park, Geonu,Woo, Hee Chul,Kim, Do Heui
, p. 1146 - 1156 (2016/02/27)
Alginate derived from macroalgae was evaluated as a biomass feedstock for the production of lactic acid using metal oxides as solid base catalysts under hydrothermal conditions. The CaO catalyst exhibited the highest catalytic performance, yielding about 13% lactic acid at 200°C for 1 h, while other metal oxide catalysts exhibited little activity. The hydration of CaO to Ca(OH)2 provides Br?nsted bases (OH-) in an aqueous medium. The lactic acid yields were proportional to the number of Br?nsted bases. The CaO catalyst demonstrated nearly similar activity when it was used for the second time and the spent catalyst was successfully regenerated by calcination. The deactivation of the CaO catalyst during subsequent repeated uses arises from the loss of the available basic sites. Plausible reaction pathways for the catalytic conversion of alginate to lactic acid over CaO are also discussed.
