João C. A. Oliveira
University of Göttingen
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Publication
Featured researches published by João C. A. Oliveira.
Chemistry: A European Journal | 2011
Sunil Pandey; Ganesh F. Jogdand; João C. A. Oliveira; Ricardo A. Mata; Pattuparambil R. Rajamohanan; Chepuri V. Ramana
The synthesis of homochiral homo-oligomers of cis- and trans-3-aminotetrahydrofuran-2-carboxylic acids (parent cis- and trans-furanoid-β-amino acids, referred to as cis-/trans-FAA) has been carried out to understand their secondary structures and their dependence on the ring heteroatom. The oligomers of two diastereomers have been shown to have a distinct left-handed helicity. The cis-FAA homo-oligomers show a 14-helix structure, in contrast to the homo-oligomers of cis-ACPC, which adopt a sheet like structure. The trans-FAA homo-oligomers were found to adopt a 12-helix structure, the same trend found in trans-ACPC homo-oligomers. With the help of ab initio calculations, the structural features of cis-ACPC and cis-FAA hexamers were compared. We believe that the more compact packing of the cis-FAA hexapeptide should be due to a more favorable interaction between the ring and the backbone amide hydrogen.
Angewandte Chemie | 2017
Hui Wang; Fabio Pesciaioli; João C. A. Oliveira; Svenja Warratz; Lutz Ackermann
Chemoselective hydroarylations were accomplished by a novel synergistic Brønsted acid/manganese(I)-catalyzed C-H activation manifold. Thus, alkynes bearing O-leaving groups could, for the first time, be employed for C-H alkenylations without concurrent β-O elimination, thereby setting the stage for versatile late-stage diversifications. Also described is the first manganese-catalyzed C-H activation in continuous flow, thus enabling efficient hydroarylations within only 20u2005minutes.
Chemistry: A European Journal | 2017
Weiping Liu; Gianpiero Cera; João C. A. Oliveira; Zhigao Shen; Lutz Ackermann
C-H alkylations with challenging β-hydrogen-containing alkyl halides were accomplished with sustainable MnCl2 as the catalyst under phosphine-ligand-free conditions. The proximity-induced benzamide C-H activation occurred with ample substrate scope through rate-determining C-H metalation, also setting the stage for manganese-catalyzed oxidative C-H methylations.
Angewandte Chemie | 2017
Joachim Loup; Daniel Zell; João C. A. Oliveira; Helena Keil; Dietmar Stalke; Lutz Ackermann
Highly enantioselective iron-catalyzed C-H alkylations by inner-sphere C-H activation were accomplished with ample scope. High levels of enantiocontrol proved viable through a novel ligand design that exploits a remote meta-substitution on N-heterocyclic carbenes within a facile ligand-to-ligand H-transfer C-H cleavage.
Journal of the American Chemical Society | 2018
Ruhuai Mei; Nicolas Sauermann; João C. A. Oliveira; Lutz Ackermann
Electrochemical oxidative C-H/N-H activations have been accomplished with a versatile cobalt catalyst in terms of [4 + 2] annulations of internal alkynes. The electro-oxidative C-H activation manifold proved viable with an undivided cell setup under exceedingly mild reaction conditions at room temperature using earth-abundant cobalt catalysts. The electrochemical cobalt catalysis prevents the use of transition metal oxidants in C-H activation catalysis, generating H2 as the sole byproduct. Detailed mechanistic studies provided strong support for a facile C-H cobaltation by an initially formed cobalt(III) catalyst. The subsequent alkyne migratory insertion was interrogated by mass spectrometry and DFT calculations, providing strong support for a facile C-H activation and the formation of a key seven-membered cobalta(III) cycle in a regioselective fashion. Key to success for the unprecedented use of internal alkynes in electrochemical C-H/N-H activations was represented by the use of N-2-pyridylhydrazides, for which we developed a traceless electrocleavage strategy by electroreductive samarium catalysis at room temperature.
Angewandte Chemie | 2018
Jiayu Mo; Thomas Müller; João C. A. Oliveira; Lutz Ackermann
C-H activation bears great potential for enabling sustainable molecular syntheses in a step- and atom-economical manner, with major advances having been realized with precious 4d and 5d transition metals. In contrast, we employed earth abundant, nontoxic iron catalysts for versatile allene annulations through a unique C-H/N-H/C-O/C-H functionalization sequence. The powerful iron catalysis occurred under external-oxidant-free conditions even at room temperature, while detailed mechanistic studies revealed an unprecedented 1,4-iron migration regime for facile C-H activations.
Chemistry: A European Journal | 2018
Youai Qiu; Julia Struwe; Tjark H. Meyer; João C. A. Oliveira; Lutz Ackermann
Catalyst- and chemical oxidant-free electrochemical azole C-H aminations were accomplished via cross-dehydrogenative C-H/N-H functionalization. The catalyst-free electrochemical C-H amination proved feasible on azoles with high levels of efficacy and selectivity, avoiding the use of stoichiometric oxidants under ambient conditions. Likewise, the C(sp3 )-H nitrogenation proved viable under otherwise identical conditions. The dehydrogenative C-H amination featured ample scope, including cyclic and acyclic aliphatic amines as well as anilines, and employed sustainable electricity as the sole oxidant.
Angewandte Chemie | 2018
Youai Qiu; Maximilian Stangier; Tjark H. Meyer; João C. A. Oliveira; Lutz Ackermann
Iridium-catalyzed electrochemical C-H activation was accomplished within a cooperative catalysis manifold, setting the stage for electrooxidative C-H alkenylations through weak O-coordination. The iridium-electrocatalyzed C-H activation featured high functional-group tolerance through assistance of a metal-free redox mediator through indirect electrolysis. Detailed mechanistic insights provided strong support for an organometallic C-H cleavage and a synergistic iridium(III/I)/redox catalyst regime, enabling the use of sustainable electricity as the terminal oxidant with improved selectivity features.
Angewandte Chemie | 2017
Sachiyo Nakanowatari; Thomas Müller; João C. A. Oliveira; Lutz Ackermann
ACS Catalysis | 2018
Cuiju Zhu; João C. A. Oliveira; Zhigao Shen; Huawen Huang; Lutz Ackermann