Premium
A Case Study of Thiourea‐Assisted Iminium Formation by Hydroxyl Anion Binding: Kinetic, Spectroscopic and Computational Evidences
Author(s) -
JusteNavarro Veronica,
Prieto Liher,
Delso Ignacio,
Manzano Rubén,
Tejero Tomas,
Reyes Efraim,
Vicario Jose L.,
Merino Pedro
Publication year - 2017
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201700986
Subject(s) - iminium , chemistry , thiourea , reactivity (psychology) , nitrone , moiety , hydroxide , catalysis , medicinal chemistry , photochemistry , organic chemistry , cycloaddition , medicine , alternative medicine , pathology
Abstract The experimental and computational study of the mechanism of the iminium‐organocatalyzed formation of N ‐hydroxypyrrolidines from nitrones, revealed up to three activation levels of the Schreiner's thiourea used as co‐catalyst, i.e: (i) formation of the iminium ion through hydroxyl anion recognition forming a stable ion pair; (ii) enolization of the nitrone through a H‐bond network and (iii) activation of the nitrone moiety towards the final ring closure. The computational model supports the mechanism and the catalytic cycle. This mechanistic rationale is supported by the lack of reactivity of preformed iminium ion with the nitrone in the absence of thiourea‐hydroxyl complex and the observed reactivity when a complex thiourea‐tetrabutylammonium hydroxide is added.