Filters

20172

More filters

20232
Reset filters

Settings

Author: Adam, Rosa × Author: Junge, Kathrin × DDC: 540 × Publisher: Cambridge : RSC ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Unprecedented selective homogeneous cobalt-catalysed reductive alkoxylation of cyclic imides under mild conditions
    (Cambridge : RSC, 2017) Cabrero-Antonino, Jose R.; Adam, Rosa; Papa, Veronica; Holsten, Mattes; Junge, Kathrin; Beller, Matthias
    The first general and efficient non-noble metal-catalysed reductive C2-alkoxylation of cyclic imides (phthalimides and succinimides) is presented. Crucial for the success is the use of [Co(BF4)2·6H2O/triphos (L1)] combination and no external additives are required. Using the optimal cobalt-system, the hydrogenation of the aromatic ring of the parent phthalimide is avoided and only one of the carbonyl groups is selectively functionalized. The resulting products, N- and aryl-ring substituted 3-alkoxy-2,3-dihydro-1H-isoindolin-1-one and N-substituted 3-alkoxy-pyrrolidin-2-one derivatives, are prepared under mild conditions in good to excellent isolated yields. Intramolecular reductive couplings can also be performed affording tricyclic compounds in a one-step process. The present protocol opens the way to the development of new base-metal processes for the straightforward synthesis of functionalized N-heterocyclic compounds of pharmaceutical and biological interest.
  • Thumbnail Image
    Item
    Cobalt-catalysed reductive C-H alkylation of indoles using carboxylic acids and molecular hydrogen
    (Cambridge : RSC, 2017) Cabrero-Antonino, Jose R.; Adam, Rosa; Junge, Kathrin; Beller, Matthias
    The direct CH-alkylation of indoles using carboxylic acids is presented for the first time. The catalytic system based on the combination of Co(acac)3 and 1,1,1-tris(diphenylphosphinomethyl)-ethane (Triphos, L1), in the presence of Al(OTf)3 as co-catalyst, is able to perform the reductive alkylation of 2-methyl-1H-indole with a wide range of carboxylic acids. The utility of the protocol was further demonstrated through the C3 alkylation of several substituted indole derivatives using acetic, phenylacetic or diphenylacetic acids. In addition, a careful selection of the reaction conditions allowed to perform the selective C3 alkenylation of some indole derivatives. Moreover, the alkenylation of C2 position of 3-methyl-1H-indole was also possible. Control experiments indicate that the aldehyde, in situ formed from the carboxylic acid hydrogenation, plays a central role in the overall process. This new protocol enables the direct functionalization of indoles with readily available and stable carboxylic acids using a non-precious metal based catalyst and hydrogen as reductant.