191480-63-4Relevant articles and documents
A broadly applicable and practical oligomeric (salen)Co catalyst for enantioselective epoxide ring-opening reactions
White, David E.,Tadross, Pamela M.,Lu, Zhe,Jacobsen, Eric N.
supporting information, p. 4165 - 4180 (2014/06/09)
The (salen)Co catalyst (4a) can be prepared as a mixture of cyclic oligomers in a short, chromatography-free synthesis from inexpensive, commercially available precursors. This catalyst displays remarkable enhancements in reactivity and enantioselectivity relative to monomeric and other multimeric (salen)Co catalysts in a wide variety of enantioselective epoxide ring-opening reactions. The application of catalyst 4a is illustrated in the kinetic resolution of terminal epoxides by nucleophilic ring-opening with water, phenols, and primary alcohols; the desymmetrization of meso epoxides by addition of water and carbamates; and the desymmetrization of oxetanes by intramolecular ring opening with alcohols and phenols. The favorable solubility properties of complex 4a under the catalytic conditions facilitated mechanistic studies, allowing elucidation of the basis for the beneficial effect of oligomerization. Finally, a catalyst selection guide is provided to delineate the specific advantages of oligomeric catalyst 4a relative to (salen)Co monomer 1 for each reaction class.
Highly enantioselective fluorescent recognition of amino acid derivatives by unsymmetrical salan sensors
Yang, Xia,Shen, Kang,Liu, Xuechao,Zhu, Chengjian,Cheng, Yixiang
supporting information; experimental part, p. 4611 - 4614 (2011/10/01)
Novel unsymmetrical salan fluorescent sensors 2a and 2b have been designed and synthesized. The chiral recognition of N-Boc-protected amino acids by 2a and 2b has been investigated. Sensor 2a possesses higher sensitivity and enantioselectivity than sensor 2b does. Job analysis and nonlinear regression results show that 2a can form a 1:1 stoichiometric complex with a N-Boc-protected amino acid. The obtained response selectivities and the association constants indicate that 2a is a highly enantioselective and sensitive fluorescent sensor toward N-Boc-protected amino acids.
Enantioselective catalytic α-alkylation of aldehydes via an S N1 pathway
Brown, Adam R.,Kuo, Wen-Hsin,Jacobsen, Eric N.
supporting information; experimental part, p. 9286 - 9288 (2010/11/03)
Primary aminothiourea derivatives are shown to catalyze enantioselective alkylation of α-arylpriopionaldehdyes with diarylbromomethane. Evidence for a stepwise, S N1 mechanism in the substitution reaction induced by anion binding to the catalyst is provided by catalyst structure-activity studies, kinetic isotope effects, linear free-energy relationship studies, and competition experiments.
