445441-94-1Relevant academic research and scientific papers
Straight Access to Indoles from Anilines and Ethylene Glycol by Heterogeneous Acceptorless Dehydrogenative Condensation
Llabres-Campaner, Pedro Juan,Ballesteros-Garrido, Rafael,Ballesteros, Rafael,Abarca, Belén
, p. 521 - 526 (2018/01/01)
The development of original strategies for the preparation of indole derivatives is a major goal in drug design. Herein, we report the first straight access to indoles from anilines and ethylene glycol by heterogeneous catalysis, based on an acceptorless dehydrogenative condensation, under noninert conditions. In order to achieve high selectivity, a combination of Pt/Al2O3 and ZnO have been found to slowly dehydrogenate ethylene glycol generating, after condensation with the amine and tautomeric equilibrium, the corresponding pyrrole-ring unsubstituted indoles.
β-Amino alcohols from anilines and ethylene glycol through heterogeneous Borrowing Hydrogen reaction
Llabres-Campaner, Pedro J.,Ballesteros-Garrido, Rafael,Ballesteros, Rafael,Abarca, Belén
supporting information, p. 5552 - 5561 (2017/08/22)
Borrowing Hydrogen (BH), also called Hydrogen Autotransfer (HA), reaction with neat ethylene glycol represents a key step in the preparation of β-amino alcohols. However, due to the stability of ethylene glycol, mono-activation has rarely been achieved. Herein, a combination of Pd/C and ZnO is reported as heterogeneous catalyst for this BH/HA reaction. This system results in an extremely air and moisture stable, and economic catalyst able to mono-functionalize ethylene glycol in water, without further activation of the diol. In this work, different diols and aromatic amines have been explored affording a new approach towards amino alcohols. This study reveals how the combination of two solid species can afford interesting catalytic properties in heterogeneous phase. ZnO activates ethylene glycol while Pd/C is the responsible of the BH/HA cycle. This catalytic system has also been found useful to dehydrogenate indoles affording indolines that undergo in situ BH/HA cycle prior to re-aromatization, representing a tandem heterogeneous process.
