Stereoselective Oxidative Rearrangement of 2-Aryl Tryptamine Derivatives
摘要:
The oxidation of 2-aryl tryptamines followed by a stereoselective rearrangement provides a versatile strategy for the synthesis of C3-quaternary oxindoles bearing a C3-aryl group. Treatment of optically active 2-aryl hydroxyindolenines with scandium trifluoromethanesulfonate in toluene at 110 degrees C leads to complete and stereoselective isomerization to the corresponding C3-aryl oxindoles which represent versatile intermediates for the synthesis of C3a-aryl hexahydropyrroloindoles.
Phosphoric Acid Catalyzed 1,2-Rearrangements of 3-Hydroxyindolenines to Indoxyls and 2-Oxindoles: Reagent-Controlled Regioselectivity Enabled by Dual Activation
作者:Eva Schendera、Stephanie Lerch、Thorsten von Drathen、Lisa-Natascha Unkel、Malte Brasholz
DOI:10.1002/ejoc.201700085
日期:2017.6.16
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