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Highly Efficient Strategy (highly + efficient_strategy)
Selected AbstractsHighly efficient strategy for enhancing taxoid production by repeated elicitation with a newly synthesized jasmonate in fed-batch cultivation of Taxus chinensis cellsBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2005Zhi-Gang Qian Abstract A highly efficient bioprocessing strategy was developed for enhancing the production of plant secondary metabolites by repeatedly eliciting a fed-batch culture with a newly synthesized powerful jasmonate analog, 2,3-dihydroxypropyl jasmonate (DHPJA). In suspension cultures of a high taxuyunnanine C (Tc)-producing cell line of Taxus chinensis, 100 ,M DHPJA was added on day 7 to fed-batch cultures with feeding of 20 g L,1 sucrose on the same day. The synergistic effect of elicitation and substrate feeding on Tc biosynthesis was observed, which resulted in higher Tc accumulation than that by elicitation or sucrose feeding alone. More interestingly, both specific Tc yield (i.e., Tc content) and volumetric yield was further improved by a second addition of 100 ,M DHPJA (on day 12) to the fed-batch cultures. In particular, with repeated elicitation and sucrose feeding the Tc volumetric yield was increased to 827 ± 29 mg L,1, which was 5.4-fold higher than that of the nonelicited batch culture. Furthermore, the above novel strategy was successfully applied from shake flask to a 1-L airlift bioreactor. A high Tc production and productivity of 738 ± 41 mg L,1 and 33.2 ± 1.9 mg L,1 d,1, respectively, was achieved, which is higher than previous reports on Tc production in bioreactors. The results suggest that the aforementioned bioprocessing strategy may potentially be applied to other cell culture systems for efficient production of plant secondary metabolites. © 2005 Wiley Periodicals, Inc. [source] Enantioselective Hydrogenation of ,-Dehydroamino Acid Esters Catalyzed by Rhodium Complexes with Chiral Bisaminophosphine LigandsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7 2010Xianfeng Sun Abstract A highly efficient strategy for the synthesis of a series of chiral bisaminophosphine ligands was well established with several remarkable features. The synthetic utility of these ligands was explored for rhodium-catalyzed asymmetric hydrogenations of ,-dehydroamino acid esters. Up to 98% ee values were achieved for the enantioselective synthesis of aminocarboxylic acids and their derivatives, which are very important chiral building blocks for the synthesis of a variety of natural products and biologically active molecules. [source] Axial Chirality Control by 2,4-Pentanediol for the Alternative Synthesis of C3*-TunePhos Chiral Diphosphine Ligands and Their Applications in Highly Enantioselective Ruthenium-Catalyzed Hydrogenation of ,-Keto EstersADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2009Xianfeng Sun Abstract A highly efficient strategy for the synthesis of a series of C3*-TunePhos chiral diphosphine ligands was well established with several remarkable features. The synthetic utility of these ligands was explored for the ruthenium-catalyzed asymmetric hydrogenation of ,-keto esters. Up to 99% ee values were achieved for the enantioselective synthesis of ,-hydroxy acid derivatives, which are very important chiral building blocks for the synthesis of a variety of natural products and biologically active molecules. [source] Stereocontrolled Intramolecular Aziridination of Glycals: Ready Access to Aminoglycosides and Mechanistic Insights from DFT StudiesCHEMISTRY - A EUROPEAN JOURNAL, Issue 5 2008Rujee Lorpitthaya Abstract Stereocontrolled intramolecular aziridination of the glycal-derived sulfamates offers a highly efficient strategy to divergently prepare aminoglycosides. Rhodium-catalyzed nitrogen-atom transfer to CC bonds formed semistable aziridines, which were subjected to various nucleophiles (C, O, S, and N) to give cyclic sulfamate-containing aminosugar derivatives selectively. The second nucleophilic displacement of sulfonyloxy moieties of [1,2,3]-oxathiazepane-2,2- dioxides allows straightforward access to aminoglycosides with selective ,- or ,-linkages. This approach is operationally simple, complements existing methods, and is a versatile protocol for the synthesis of polyfunctionalized amino sugars. In addition, the mechanism of the rhodium-catalyzed intramolecular aziridination of glycals and its ring-opening reaction was extensively studied by using DFT calculations. [source] | ||||||||||