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71.
Dr. Qilei Song Hong Qiu Lijun Liu Prof. Dr. Guangzhao Zhang Prof. Dr. Frédéric Peruch Prof. Dr. Stéphane Carlotti Prof. Dr. Junpeng Zhao 《Angewandte Chemie (International ed. in English)》2023,62(18):e202300187
One-step sequence-selective block copolymerization requires stringent catalytic control of monomers relative activity and enchainment order. It has been especially rare for AnBm-type block copolymers from simple binary monomer mixtures. Here, ethylene oxide (EO) and N-sulfonyl aziridine (Az) compose a valid pair provided with a bicomponent metal-free catalyst. Optimal Lewis acid/base ratio allows the two monomers to strictly block-copolymerize in a reverse order (EO-first) as compared with the conventional anionic route (Az-first). Livingness of the copolymerization facilitates one-pot synthesis of multiblock copolymers by addition of mixed monomers in batches. Calculation results reveal that a Janus effect of Lewis acid on the two monomers is key to enlarge the activity difference and reverse the enchainment order. 相似文献
72.
A new type of chiral cobalt salen complexes bearing BF3 Lewis acid proved to be reactive and enantioselective in the hydrolytic resolution of terminal epoxides. The polymer type salen catalysts also showed a high enantioselectivity in the same reaction. 相似文献
73.
Highly efficient ring opening reactions of epoxides with deactivated aromatic amines catalyzed by heteropoly acids in water 总被引:1,自引:0,他引:1
Najmedin Azizi 《Tetrahedron》2007,63(4):888-891
Heteropoly acid was found to be an effective and efficient catalyst for the ring opening reaction of epoxides with various aromatic amines to produce the corresponding β-amino alcohols in moderate to excellent yields in water. This method provides a new and efficient protocol in terms of mild reaction conditions, clean reaction profiles, small quantity of catalyst, and simple work-up procedure. 相似文献
74.
The mixed-valent oxo-centered triiron(III, III, II) trifluoroacetate complex [Fe2IIIFeIIO(O2CCF3)6(H2O)3] was prepared by reacting anhydrous iron(III) chloride with boiling trifluoroacetic acid under nitrogen. The non-hygroscopic and readily available mixed-valent triiron trifluoroacetate complex was found to be an efficient catalyst for the regioselective rearrangement of epoxides. A number of carbonyl compounds formed via the rearrangement of epoxides could be obtained by a simple filtration of the reaction mixture through a short plug of silica gel. 相似文献
75.
A stereoselective synthesis of pentacyclic steroids has been achieved. Starting from commercially available cholic acid 1, followed by asymmetric epoxidation and by stereoselective epoxide ring opening, employing nucleophilic species, the corresponding products were afforded in good yields. The compounds were being evaluated for their biological activity. 相似文献
76.
The reaction of glycidic amides with various functionalized nitriles to afford norstatine analogs in a regio- and diastereoselective fashion (43-99% yield) is described. Utilizing this chemistry, a 20 membered solution phase library was prepared in two steps featuring three points of diversity. 相似文献
77.
Xue-qiang Yin 《Tetrahedron letters》2005,46(44):7535-7538
Carbocyclic nucleosides substituted at the C-6′ position are receiving increasing attention. Chiral synthetic accessibility to the biologically promising 6′-β-fluoroaristeromycin is lacking. Its preparation and that of the 5′-nor analogue are described. Along the way, a new method to aristeromycin arose as an outgrowth of a requisite structure proof. 相似文献
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