Urea Anions: Simple, Fast, and Selective Catalysts for Ring-Opening Polymerizations
作者:Binhong Lin、Robert M. Waymouth
DOI:10.1021/jacs.6b11864
日期:2017.2.1
the reactivities of several diaryl urea anions correlated to the electron-withdrawing substituents on the aryl rings. With the appropriate urea anions, the polymerizations reached high conversions (∼90%) at room temperature within seconds (1-12 s), yielding polymers with narrow molecular weight distributions (Đ = 1.06 to 1.14). These versatile catalysts are simple to prepare, easy to use, and exhibit
Disclosed are compounds which have been identified as inhibitors of phosphate transport. Many of the compounds are represented by Structural Formula (I):
Ar
1
—W—X—Y—Ar
2
;
or a pharmaceutically acceptable salt thereof. Ar
1
and Ar
2
are independently a substituted or unsubstituted aryl group or an optionally substituted five membered or six membered non-aromatic heterocylic group fused to an optionally substituted monocylic aryl group. W and Y are independently a covalent bond or a C1-C3 substituted or unsubstituted alkylene group. X is a heteroatom-containing functional group, an aromatic heterocyclic group, substituted aromatic heterocyclic group, non-aromatic heterocyclic group, substituted non-aromatic heterocyclic group, an olefin group or a substituted olefin group. Also disclosed are methods of treating a subject with a disease associated with hyperphosphatemia, as well as a disease mediated by phosphate-transport function. The methods comprise the step of administering an effective amount of the one of the compounds described above.
Techniques regarding the synthesis of polyesters and/or polycarbonates through one or more ring-opening polymerizations conducted within a flow reactor and facilitated by a urea anion catalyst and/or a thiourea catalyst are provided. For example, one or more embodiments can comprise a method, which can comprise polymerizing, via a ring-opening polymerization within a flow reactor, a cyclic monomer in the presence an organocatalyst comprising a urea anion.
Brønsted Base/Lewis Acid Cooperative Catalysis in the Enantioselective Conia-Ene Reaction
作者:Ting Yang、Alessandro Ferrali、Filippo Sladojevich、Leonie Campbell、Darren J. Dixon
DOI:10.1021/ja9004859
日期:2009.7.8
A mutually compatible and cooperative combination of copper(I) triflate and bifunctional 9-amino-9-deoxyepicinchona-derived urea compounds for the enantioselective Conia-ene cyclization of alkyne-tethered beta-ketoester substrates is reported. The reaction is efficient, broad in scope, and easy to perform and allows access to chiral methylenecyclopentane products with high enantiocontrol. The transformation illustrates the concept of combining inactive precatatysts with inactive transition-metal-ion complexes in situ to reversibly create a catalytically active combination of the two.