@article {https://doi.org/10.1002/cctc.201900416, title = {Planar-Chiral [2.2]Paracyclophane-Based Pyridonates as Ligands for Tantalum-Catalyzed Hydroaminoalkylation}, journal = {ChemCatChem}, volume = {11}, number = {21}, year = {2019}, pages = {5264-5268}, abstract = {Abstract By using planar chiral [2.2]paracyclophane-containing N,O-chelating ligands for tantalum-catalyzed hydroaminoalkylation, one of the most versatile catalytic systems for this reaction to date was obtained. Convenient Csp3-Csp3 bond formation of amines with terminal and internal alkenes was enabled by the same in situ synthesized catalytic system of [2.2]paracyclophane-based pyridonates and Ta(CH2TMS)3Cl2 that shows also very promising results for N-containing heterocycles.}, keywords = {ALKENES, AMINES, Cyclophanes, Green chemistry, tantalum}, doi = {https://doi.org/10.1002/cctc.201900416}, url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/cctc.201900416}, author = {Braun, Carolin and Nieger, Martin and Br{\"a}se, Stefan and Schafer, Laurel L.} } @article {31534, title = {Catalytic and Atom-Economic C -C Bond Formation: Alkyl Tantalum Ureates for Hydroaminoalkylation}, journal = {Angewandte Chemie International Edition}, volume = {57}, year = {2018}, pages = {3469-3472}, abstract = {
Abstract Atom-economic and regioselective C \−C bond formation has been achieved by rapid C\−H alkylation of unprotected secondary arylamines with unactivated alkenes. The combination of Ta(CH2SiMe3)3Cl2, and a ureate N,O-chelating-ligand salt gives catalytic systems prepared in situ that can realize high yields of β-alkylated aniline derivatives from either terminal or internal alkene substrates. These new catalyst systems realize C\−H alkylation in as little as one hour and for the first time a 1:1 stoichiometry of alkene and amine substrates results in high yielding syntheses of isolated amine products by simple filtration and concentration.
}, keywords = {AMINES, C-H activation, HYDROAMINOALKYLATION, tantalum alkyls, ureates}, doi = {10.1002/anie.201712668}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201712668}, author = {DiPucchio, Rebecca C. and Ro{\c s}ca, Sorin-Claudiu and Schafer, Laurel L.} } @article {2495, title = {Broadening the Scope of Group 4 Hydroamination Catalysis Using a Tethered Ureate Ligand}, journal = {Journal of the American Chemical Society}, volume = {131}, number = {51}, year = {2009}, note = {ISI Document Delivery No.: 543YATimes Cited: 12Cited Reference Count: 34Leitch, David C. Payne, Philippa R. Dunbar, Christine R. Schafer, Laurel L.}, month = {Dec}, pages = {18246-+}, type = {Article}, abstract = {A broadly applicable group-4-based precatalyst for the hydroamination of primary and secondary amines was developed. Screening experiments involving a series of amide and urea proligands led to the discovery of a tethered bis(ureate) zirconium complex with unprecedented reactivity in the intermolecular hydroamination of alkynes and the intramolecular hydroamination of alkenes. This catalyst system is effective with primary and secondary amines, 1,2-disubstituted alkenes, and heteroatom-containing functional groups, including ethers, silanes, amines, and heteroaromatics. The gem-disubstituent effect is not required for cyclization. The catalyst is generally regioselective for the anti-Markovnikov product of intermolecular alkyne hydroamination, and chemoselective for hydroamination over alpha-alkylation when forming 6- and 7-membered rings from aminoalkenes.}, keywords = {ALKYNES, AMIDATE COMPLEXES, AMINES, AMINOALKENES, BOND FORMATION, INTRAMOLECULAR HYDROAMINATION, METAL-CATALYSTS, TITANIUM, UNACTIVATED ALKENES, ZIRCONIUM}, isbn = {0002-7863}, url = {