Related Experiment Video
Updated: Jul 16, 2026

Synthesis of Information-bearing Peptoids and their Sequence-directed Dynamic Covalent Self-assembly
Published on: February 6, 2020
Synthesis of Mechanically Isomeric Rotaxanes from Cross-Chain Bridging Cryptands and a Secondary Ammonium Ion
Kento Ohtani1, Hiroki Fujihara1, Kohta Nakashima1
1Department of Materials Science and Engineering, Faculty of Engineering, University of Fukui, Bunkyo, Fukui 910-8507, Japan.
Abstract:
We selectively synthesized mechanically isomeric (pseudo)[2]rotaxanes possessing two types of entangled structures: C2-symmetric [2]rotaxane and nonsymmetric (C1-symmetric) pseudo[2]rotaxane. The first structure was synthesized from a small cross-chain bridging cryptand possessing 24- and 25-membered macrocycles via selective formation of the C2-pseudorotaxane. The second structure was obtained from a large cross-chain bridging cryptand bearing 30- and 31-membered macrocycles through insufficient end capping of the pseudorotaxanes and kinetic resolution of the end-capped pseudorotaxanes.
Related Concept Videos
Thermal Electrocyclic Reactions: Stereochemistry
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.
Cycloaddition Reactions: MO Requirements for Thermal Activation
Electrophilic Addition to Alkynes: Halogenation
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Preparation of Amines: Alkylation of Ammonia and Amines
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Preparation of Alkynes: Alkylation Reaction
Alkylation of terminal alkynes with primary alkyl halides in the presence of a strong base like sodium amide is one of the common methods for the synthesis of longer carbon-chain alkynes. For example, treatment of 1-propyne with sodium amide followed by reaction with ethyl bromide yields 2-pentyne.
Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)
