The stereoselective synthesis of trisubstituted 2-trifluoromethyl pyrrolidines by asymmetric Michael addition/hydrogenative cyclization is described. The direct organocatalytic addition of 1,1,1-trifluoromethylketones to nitroolefins proceeds under mild reaction conditions and low catalyst loadings to provide Michael adducts in high yield with excellent
Chemistry (Weinheim an der Bergstrasse, Germany), 9(2), 407-414 (2003-01-18)
We examined the catalytic activity of substituted thioureas in a series of Diels-Alder reactions and 1,3-dipolar cycloadditions. The kinetic data reveal that the observed accelerations in the relative rates are more dependent on the thiourea substituents than on the reactants
[reaction: see text] A combination of NMR, IR, and ab initio techniques reveals the striking structural similarities of an exemplary H-bonded complex of an N-acyloxazolidinone with an N,N'-disubstituted electron-poor thiourea and the corresponding Lewis acid complex. Although the H-bond association
Chemical communications (Cambridge, England), 50(47), 6281-6284 (2014-05-07)
Using a prototypical Diels-Alder reaction as benchmark, we show that dicationic halogen-bond donors are capable of activating a neutral organic substrate. By various comparison experiments, the action of traces of acid or of other structural features of the halogen-bond donor
Boronate ureas benefit from internal Lewis acid coordination of the urea cabonyl oxygen and the strategically placed boron. As a result of this structural feature, boronate ureas can be rendered more acidic than conventional urea hydrogen bond donor catalysts.