Scientific article
Open access

Configurational Lability of Imino-Substituted Ethano Tröger Bases. Insight on the Racemization Mechanism

Published inHelvetica Chimica Acta, vol. 102, no. 3, e1900021
Publication date2019

Polycyclic indoline‐benzodiazepines are afforded in one step by the reaction of Tröger bases with N‐sulfonyl‐1,2,3‐triazoles under Rh(II) catalysis. After α‐imino carbene formation, the process involves a cascade of [1,2]‐Stevens rearrangement, Friedel‐Crafts, Grob fragmentation, and aminal formation reactions. It is highly diastereoselective (d.r. >49:1, four stereocenters incl. two bridgehead N‐atoms). However and in contrast with other reported carbene additions to these moieties, full racemization occurs when enantiopure Tröger bases are used as substrates. To pinpoint the origin of this unexpected behavior, a key elemental step of the mechanism was evaluated and tested. Interestingly, it is not only the initial ring‐opening but also the latter reversible Mannich reaction of the imino‐substituted ethano Tröger base intermediate that is responsible for the loss of enantiospecificity.

Research group
Citation (ISO format)
BOSMANI, Alessandro, GUARNIERI IBANEZ, Alejandro José, LACOUR, Jérôme. Configurational Lability of Imino-Substituted <i>Ethano Tröger</i> Bases. Insight on the Racemization Mechanism. In: Helvetica Chimica Acta, 2019, vol. 102, n° 3, p. e1900021. doi: 10.1002/hlca.201900021
Main files (2)
Article (Published version)
Article (Accepted version)
ISSN of the journal0018-019X

Technical informations

Creation03/21/2019 1:09:00 PM
First validation03/21/2019 1:09:00 PM
Update time03/15/2023 4:01:39 PM
Status update03/15/2023 4:01:39 PM
Last indexation01/17/2024 5:09:58 AM
All rights reserved by Archive ouverte UNIGE and the University of GenevaunigeBlack