148615-28-5Relevant articles and documents
Combination of bio- and chemocatalysis for dynamic kinetic resolution: The assembly strategies for nanozeolite-modified flow microchannel reactors
Wang, Zhoujun,Li, Xiang,Wang, Wanlu,Tang, Yi,Zhang, Yahong
, p. 1 - 8 (2013)
The combination of bio- and chemocatalysts in one-pot is regarded as a breakthrough both for development of new catalytic concepts and for preparation of high-value chemicals. Zeolite nanocrystals (nanozeolites) have been proved as the most used chemical catalysts and as promising supports for enzyme immobilization. These capabilities of nanozeolites endow them with new possibilities for constructing desired platforms for the combination of bio- and chemocatalysis. In this article, several strategies are proposed to develop a one-pot flow microchannel reactor (MCR) by combining enzyme and chemocatalysis via a nanozeolite assembly approach, and the compatibilities of different types of active centers in various assembly strategies are systematically discussed on the basis of the catalytic results of dynamic kinetic resolution (DKR) of sec-alcohol. By precisely controlling the spatial distribution and the ratio of acidic and enzymatic active sites, as well as the reaction conditions, nanozeolite-modified MCR can achieve fast and highly selective one-pot DKR of sec-alcohol within 30 min.
Shell Cross-Linked Micelles as Nanoreactors for Enantioselective Three-Step Tandem Catalysis
Kuepfert, Michael,Cohen, Aaron E.,Cullen, Olivia,Weck, Marcus
supporting information, p. 18648 - 18652 (2018/11/23)
Functionalized amphiphilic poly(2-oxazoline)-based triblock copolymers that assemble into shell cross-linked micelles (SCMs) are described. These micelles permit the site isolation of three incompatible catalysts through compartmentalization, thereby enabling three-step non-orthogonal tandem processes in one pot. In particular, the acid-catalyzed ketal hydrolysis to prochiral ketones proceeded in the hydrophilic corona, followed by the Rh-catalyzed asymmetric transfer hydrogenation to enantio-enriched alcohols in the cross-linked shell, and nucleophilic base-catalyzed acylation in the hydrophobic core. The catalysts are positioned in close proximity on a single micelle support to take advantage of the intramicellar substrate diffusion, yet they are sufficiently spaced apart from each other in physically distinct microenvironments. These compartmentalized micelles are substrate selective and, on a basic level, mimic compartmentalized catalytic architectures found in nature.
Core-Shell Composite as the Racemization Catalyst in the Dynamic Kinetic Resolution of Secondary Alcohols
Wang, Jie,Do, Dong-Minh,Chuah, Gaik-Khuan,Jaenicke, Stephan
, p. 247 - 254 (2013/03/13)
Beta-Silicalite-1 core-shell microcomposites with controllable shell thickness were synthesized and used as racemization catalysts in the one-pot dynamic kinetic resolution (DKR) of secondary alcohols by using lipase-catalyzed transesterification. The inert Silicalite-1 shell covered the external acidic sites of the Beta zeolite core, suppressing dehydration and non-enantioselective transesterification of the alcohol. The alcohols could penetrate the Silicalite-1 shell to access the acidic sites at the core Beta for racemization, however, the enzymatically formed (R)-esters were excluded owing to their larger size. As a result, the high ee of the (R)-ester products was conserved and dehydration side products were minimized. Owing to the shape selective nature of the composite racemization catalyst, small and readily available acyl donors could be used in the enzyme-catalyzed transesterification to obtain the esters with high enantiopurity. The DKR of 1-phenylethanol with isopropenyl acetate using an optimized core-shell catalyst, CS-60, gave 92% selectivity to ester formation and the desired (R)-1-phenylethyl acetate was formed with 94% ee.
