Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Cycloaddition Reactions: MO Requirements for Photochemical Activation

Cycloaddition Reactions: MO Requirements for Photochemical Activation

Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.

Photochemical Electrocyclic Reactions: Stereochemistry

Photochemical Electrocyclic Reactions: Stereochemistry

The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation

Thermal and Photochemical Electrocyclic Reactions: Overview

Thermal and Photochemical Electrocyclic Reactions: Overview

Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.

Cationic Chain-Growth Polymerization: Mechanism

Cationic Chain-Growth Polymerization: Mechanism

The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the...

Peptide Bonds

Peptide Bonds

A peptide bond covalently attaches amino acids through a dehydration reaction. One amino acid's carboxyl group and another amino acid's amino group combine, releasing a water molecule. The resulting bond is the peptide bond. The products that such linkages form are peptides. As more amino acids join this growing chain, the resulting chain is a polypeptide. Each polypeptide has a free amino group at one end. This end has the N-terminal, or the amino-terminal, and the other end has a free...

Cycloaddition Reactions: Overview

Cycloaddition Reactions: Overview

Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Programmable Steric Control of Collagen Peptide-to-Fiber Assembly.

Journal of the American Chemical Society·2026

Same author

Conditional Localization Pharmacology Manipulates the Cell Cycle with Spatiotemporal Precision.

Journal of the American Chemical Society·2026

Same author

Precision Therapeutics Across Cancer, Immunology, and Pain.

ACS medicinal chemistry letters·2026

Same author

Catalytic Strategies in Oncology and Autoimmunity: From EGFR Resistance to RNA-Guided Screening.

ACS medicinal chemistry letters·2026

Same author

Selective TYK2 Inhibition, Prenatal Cell Diagnostics, and Biomarker-Guided Immunotherapy: Expanding Precision Medicine.

ACS medicinal chemistry letters·2026

Same author

From Multivalency to Biomarker-Guided Delivery: Integrating Breakthroughs for the Future of Targeted Protein Degradation.

ACS medicinal chemistry letters·2026

Same journal

Electrochemical Dearomative <i>ipso</i>-Cyclization of Indolyl-ynones: A Direct Access to Trifluoromethyl/Selenyl-Spirooxindoles.

Organic letters·2026

Same journal

Photoinduced Radical Epoxidation of <i>N</i>-Alkoxyphthalimides with Allylic Peroxides.

Organic letters·2026

Same journal

B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>-Catalyzed Ring-Opening Reaction of Bicyclo[1.1.0]butanes with Silyl Ketene Imines.

Organic letters·2026

Same journal

<i>N</i>-Sulfonylaminophthalimide-Catalyzed Aerobic Oxidative Cleavage of α-C(sp<sup>3</sup>)-H and β,γ-C(sp<sup>3</sup>)-C(sp<sup>3</sup>) Bonds of Tertiary Amines.

Organic letters·2026

Same journal

<i>O</i>-Alkylisourea-Enabled Nickel/Photoredox-Catalyzed Giese Reaction.

Organic letters·2026

Same journal

Direct Assembly of Angular 5-5-5 Tricyclic Skeletons via a Rh(III)-Catalyzed C-H Activation/Annulation Cascade.

Organic letters·2026

See all related articles

Search research articles

Related Experiment Video

Updated: Sep 5, 2025

Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation

Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation

Published on: August 1, 2018

Solid-Phase Photochemical Peptide Homologation Cyclization.

Michael B Elbaum¹, Mahmoud A Elkhalifa¹, Gary A Molander¹

¹Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States.

Organic Letters

|July 11, 2022

Summary

This summary is machine-generated.

This study introduces a novel photochemical method for solid-phase peptide synthesis, enabling the creation of new carbon-carbon bonds. This breakthrough facilitates the development of peptide macrocycles and therapeutic agents.

More Related Videos

Constructing Cyclic Peptides Using an On-Tether Sulfonium Center

Constructing Cyclic Peptides Using an On-Tether Sulfonium Center

Published on: September 28, 2022

Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly

Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly

Published on: February 6, 2020

Related Experiment Videos

Last Updated: Sep 5, 2025

Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation

Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation

Published on: August 1, 2018

Constructing Cyclic Peptides Using an On-Tether Sulfonium Center

Constructing Cyclic Peptides Using an On-Tether Sulfonium Center

Published on: September 28, 2022

Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly

Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly

Published on: February 6, 2020

Area of Science:

Organic Chemistry
Medicinal Chemistry
Peptide Chemistry

Background:

Forming central C(sp3)-C(sp3) bonds in peptide backbones is crucial for drug discovery.
Existing methods lack photochemical, solid-phase approaches for Asp/Glu side chain decarboxylation and macrocyclization.

Purpose of the Study:

To develop a novel photochemical method for solid-phase peptide modification.
To enable decarboxylation of Asp and Glu side chains and subsequent macrocyclization.

Main Methods:

Utilized electron-donor-acceptor complexes of Hantzsch ester and on-resin peptide N-hydroxyphthalimide radical precursors.
Employed photochemistry for radical generation and C-C bond formation on solid phase.

Main Results:

Successfully generated radicals from Asp and Glu side chains on solid-phase peptides.
Demonstrated two-carbon homologations and cyclizations, forming peptide macrocycles.
Validated the method with Atosiban and RGDf peptide analogs.

Conclusions:

This new photochemical strategy provides a versatile platform for peptide backbone modification.
Enables the synthesis of complex peptide macrocycles previously inaccessible via solid-phase methods.
Offers potential for developing novel therapeutics and chemical probes.