906370-95-4Relevant academic research and scientific papers
Novel Functional Hollow and Multihollow Organic Microspheres: Enhanced Efficiency in a Complex, Heterogeneous, Asymmetric, Three-Component/Triple Organocascade Reaction
Dai, Fuqiang,Zhao, Zhiwei,Xie, Guangxin,Feng, Dandan,Ma, Xuebing
, p. 89 - 93 (2017/01/17)
The pioneered construction of monodisperse hollow and multihollow J?rgensen–Hayashi-functionalized microspheres with a well-defined spherical morphology, high surface area, and large pore volume were developed by initial dispersion copolymerization of the J?rgensen–Hayashi organocatalyst with acrylamide and styrene monomers cross-linked by p-divinylbenzene and ethylene glycol dimethacrylate, respectively, on the surface of poly(styrene/acrylic acid) (PS) microspheres to form core–shell structures, followed by removal of the PS core by etching in organic solvents. The as-prepared hollow and multihollow microspheres were able to achieve better mass transfer in a complex heterogeneous asymmetric three-component/triple cascade reaction and provided the products in good yields (31–61 %) with excellent stereoselectivities (80:20–93:7 dr, >99 % ee).
A general approach for preparation of polymer-supported chiral organocatalysts via acrylic copolymerization
Kristensen, Tor E.,Vestli, Kristian,Jakobsen, Martin G.,Hansen, Finn K.,Hansen, Tore
supporting information; experimental part, p. 1620 - 1629 (2010/04/29)
(Figure Presented) Polymer-supported chiral organocatalysts, as well as most other forms of immobilized catalysts, are traditionally prepared by a postmodification approach where modified catalyst precursors are anchored onto prefabricated polymer beads. Herein, we report an alternative and more scalable approach where polymer-supported chiral enamine and iminium organocatalysts are prepared in a bottom-up fashion where methacrylic functional monomers are prepared in an entirely nonchromatographic manner and subsequently copolymerized with suitable comonomers to give cross-linked polymer beads. All syntheses have been conducted on multigram scale for all intermediates and finished polymer products, and the catalysts have proven successful in reactions taking place in solvents spanning a wide range of solvent polarity. While polymer-supported proline and prolineamides generally demonstrated excellent results and recycling robustness in asymmetric aldol reactions of ketones and benzaldehydes, the simplest type of Joargensen/Hayashi diarylprolinol TMS-ether showed excellent selectivity, but rather sluggish reactivity in the Enders-type asymmetric cascade. The polymer-supported version of the first-generation MacMillan imidazoHdinone had a pattern of reactivity very similar to that of the monomeric catalyst, but is too unstable to allow recycling.
Asymmetric synthesis of polyfunctionalized mono-, Bi-, and tricyclic carbon frameworks via organocatalytic domino reactions
Enders, Dieter,Huettl, Matthias R. M.,Raabe, Gerhard,Bats, Jan W.
experimental part, p. 267 - 279 (2009/04/08)
An asymmetric organocatalytic multi-component domino reaction is used as a key process for the stereoselective synthesis of polysubstituted mono- and bicyclic cyclohexene-carbaldehydes. Furthermore, the extension of the domino reaction and further synthetic transformations of the cascade products were investigated. The combination of the three-step cascade with an intramolecular Diels-Alder reaction opens up an entry to tricyclic decahydroacenaphthylene and decahydrophenalene skeletons, which are valuable characteristic carbon cores of natural products.
