27309-62-2Relevant academic research and scientific papers
Phosphoric Acid Catalyzed 1,2-Rearrangements of 3-Hydroxyindolenines to Indoxyls and 2-Oxindoles: Reagent-Controlled Regioselectivity Enabled by Dual Activation
Schendera, Eva,Lerch, Stephanie,von Drathen, Thorsten,Unkel, Lisa-Natascha,Brasholz, Malte
supporting information, p. 3134 - 3138 (2017/06/21)
A common synthetic route to indoxyl and 2-oxindole alkaloids utilizes the oxidation of indoles to 3-hydroxyindolenines, followed by acid-mediated 1,2-rearrangement. However, controlling the regioselectivity is often challenging and there is an ongoing need for new reaction conditions allowing to steer product selectivity. We report herein that phosphoric acids are ideal organocatalysts for the highly regioselective 1,2-rearrangement of 3-hydroxyindolenines to 2-oxindoles, with predictable product selectivity arising from an efficient dual activation mode.
An asymmetric pericyclic cascade approach to 3-alkyl-3-aryloxindoles: Generality, applications and mechanistic investigations
Richmond, Edward,Ling, Kenneth B.,Duguet, Nicolas,Manton, Lois B.,elebi-?lcüm, Nihan,Lam, Yu-Hong,Alsancak, Sezen,Slawin, Alexandra M. Z.,Houk,Smith, Andrew D.
, p. 1807 - 1817 (2015/02/19)
The reaction of L-serine derived N-arylnitrones with alkylarylketenes generates asymmetric 3-alkyl-3-aryloxindoles in good to excellent yields (up to 93%) and excellent enantioselectivity (up to 98% ee) via a pericyclic cascade process. The optimization, scope and applications of this transformation are reported, alongside further synthetic and computational investigations. The preparation of the enantiomer of a Roche anti-cancer agent (RO4999200) 1 (96% ee) in three steps demonstrates the potential utility of this methodology.
