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

Intramolecular Claisen Condensation of Dicarboxylic Esters: Dieckmann Cyclization

Intramolecular Claisen Condensation of Dicarboxylic Esters: Dieckmann Cyclization

Dieckmann cyclization is an intramolecular Claisen condensation of diesters. The reaction occurs in the presence of a base and generates a cyclic β-ketoester as the final product. Commonly, 1, 6 and 1, 7-diesters are preferred substrates for the reaction since the generated five, and six-membered cyclic β-keto esters are particularly more stable.

Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry

Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry

Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.

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 Electrocyclic Reactions: Stereochemistry

Thermal Electrocyclic Reactions: Stereochemistry

The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.

Diels–Alder Reaction Forming Cyclic Products: Stereochemistry

Diels–Alder Reaction Forming Cyclic Products: Stereochemistry

The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.

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.

You might also read

Related Articles

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

Sort by

Same author

Highly Selective and Modular Assembly of Densely Substituted Tetrahydrofurans.

Journal of the American Chemical Society·2026

Same author

Reactions of Strained Cycloalkanes with Radicals and Diradicaloids: The Roles of Diradical Character and Strain Release.

Journal of the American Chemical Society·2026

Same author

Determining Quantum Mechanical Methods Suitable for Quantitative Modeling of Hydrogen Atom Transfer by Halogen Atoms.

Journal of chemical theory and computation·2026

Same author

Photo-Triggered, Fast, and Fluorogenic Thiophene-Based Cycloalkynes for the Bioorthogonal Fluorescent Labeling of 1,3-Dipole-Tagged Molecules in No-Wash Conditions.

Angewandte Chemie (International ed. in English)·2026

Same author

Cobaloxime-catalysed regiodivergent hydrogen atom transfer for alkenyl and allylic carbamoylation with branched alkenes.

Nature communications·2026

Same author

Non-Enzymatic Formation of Chaxines and Natural Steroidal Derivatives via Ergosterol Air Oxidation.

The Journal of organic chemistry·2026

Search research articles

Related Experiment Video

Updated: Nov 24, 2025

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Published on: February 7, 2019

A Polyketide Cyclase That Forms Medium-Ring Lactones.

De-Wei Gao, Cooper S Jamieson, Gaoqian Wang¹

¹State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai, China.

Journal of the American Chemical Society

|December 22, 2020

Summary

Researchers discovered a thioesterase enzyme, DcsB, that efficiently catalyzes medium-ring lactonizations. This enzyme, from the decarestrictine C1 pathway, shows broad substrate scope and offers potential as a biocatalyst for challenging lactone synthesis.

More Related Videos

Enzymatic Cascade Reactions for the Synthesis of Chiral Amino Alcohols from L-lysine

Enzymatic Cascade Reactions for the Synthesis of Chiral Amino Alcohols from L-lysine

Published on: February 16, 2018

Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers

Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers

Published on: December 16, 2022

Related Experiment Videos

Last Updated: Nov 24, 2025

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Efficient Construction of Drug-like Bispirocyclic Scaffolds Via Organocatalytic Cycloadditions of α-Imino γ-Lactones and Alkylidene Pyrazolones

Published on: February 7, 2019

Enzymatic Cascade Reactions for the Synthesis of Chiral Amino Alcohols from L-lysine

Enzymatic Cascade Reactions for the Synthesis of Chiral Amino Alcohols from L-lysine

Published on: February 16, 2018

Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers

Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers

Published on: December 16, 2022

Area of Science:

Biochemistry
Organic Chemistry
Enzymology

Background:

Medium-ring lactones are difficult to synthesize due to unfavorable cyclization energetics.
The decarestrictine C1 biosynthetic pathway involves complex natural product formation.

Purpose of the Study:

To identify and characterize enzymes involved in medium-ring lactone formation.
To explore the potential of DcsB as a biocatalyst for lactonization reactions.

Main Methods:

Enzyme discovery and isolation from the decarestrictine C1 pathway.
Biochemical assays to assess DcsB activity and substrate scope.
X-ray crystallography and computational modeling to elucidate the catalytic mechanism.

Main Results:

Discovery of thioesterase DcsB, an enzyme that efficiently catalyzes medium-ring lactonizations.
DcsB exhibits broad substrate promiscuity with linear precursors of varying lengths and substituents.
Structural and computational analyses revealed the molecular basis for DcsB's catalytic activity.

Conclusions:

DcsB is a highly effective enzyme for medium-ring lactonization, overcoming synthetic challenges.
The enzyme's broad substrate scope makes it a promising biocatalyst for diverse lactone synthesis applications.
Understanding DcsB's mechanism provides insights into enzymatic control of challenging cyclizations.