Related Experiment Video
Updated: Jun 15, 2026

Preparation of N-(2-alkoxyvinyl)sulfonamides from N-tosyl-1,2,3-triazoles and Subsequent Conversion to Substituted Phthalans and Phenethylamines
Published on: January 3, 2018
Synthesis of hexa- and pentasubstituted diketopiperazines from sterically hindered amino acids
Zachary Z Brown1, Christian E Schafmeister
1Chemistry Department, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Abstract:
Steric hindrance assists in the formation of hindered diketopiperazines using acyl-transfer coupling. In acyl-transfer coupling, the carboxylate of an unprotected N-alkylamino acid attacks an active ester to form a transient anhydride that undergoes an O,N acyl transfer to form a tertiary amide. If the active ester is part of an N-alkylamino acid it will form a diketopiperazine. It is demonstrated here that acyl-transfer coupling can assemble highly functionalized bis-peptides bearing a functional group on every monomer.
Related Concept Videos
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group with both...
Stability of Substituted Cyclohexanes
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Criteria for Aromaticity and the Hückel 4n + 2 Rule
For the first time, Eric Hückel, a German chemical physicist, derived a set of structural features for a compound to be classified as aromatic. This is now known as Hückel’s rule or the 4n + 2 rule.
Disubstituted Cyclohexanes: cis-trans Isomerism
In cyclohexane, the substituents can occupy different positions generating distinct isomers.
Directing and Steric Effects in Disubstituted Benzene Derivatives
Diels–Alder Reaction Forming Cyclic Products: Stereochemistry

