Related Experiment Video
Updated: Nov 29, 2025

Constructing Cyclic Peptides Using an On-Tether Sulfonium Center
Published on: September 28, 2022
Amidine Functionality As a Conformational Probe of Cyclic Peptides
Sungjoon Huh1, Solomon D Appavoo1, Andrei K Yudin1
1Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada.
Abstract:
The amidine functionality switches between hydrogen bond donor and acceptor roles depending on pH. Herein, the amidine was incorporated to select amides in cyclo(d-Ala-Pro-d-Phe-Pro-Gly). The unprotonated amidine-containing macrocyclic conformation resembles its oxoamide counterpart. Upon protonation, minimal alterations in the macrocyclic conformation were observed despite changes to the hydrogen bond network. The amidine disrupts hydrogen bonding at minimal steric cost, making it a useful functionality to study the effect of hydrogen bonding on the macrocyclic conformation.
Related Concept Videos
NMR Spectroscopy Of Amines
Mass Spectrometry of Amines
Amines undergo fragmentation through α cleavage, producing nitrogen-containing cations—iminium ions—and alkyl radicals. Mass spectra of aromatic and cyclic aliphatic amines exhibit...
Nomenclature of Primary Amines
Structure of Amines
Amines to Amides: Acylation of Amines
Next, the second equivalent of amine serves as a Brønsted base and deprotonates the quaternary...
Amines: Introduction

