Cyclopentannulated Dihydrotetraazapentacenes
Robin Heckershoff1, Steffen Maier1, Thomas Wurm1
1Organisch-Chemisches Institut (OCI), Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|January 12, 2022
Summary
Transition-metal catalysts enable the cyclization of a tetraazapentacene derivative. Silyl group migration during this reaction influences the final molecular structure and packing, impacting material properties.
Area of Science:
- Organic Chemistry
- Materials Science
- Catalysis
Background:
- N,N'-dihydrotetraazapentacenes (TIPS-TAP-H2) are complex organic molecules with potential optoelectronic applications.
- Controlling the cyclization and functionalization of such polycyclic aromatic systems is crucial for tuning their properties.
Purpose of the Study:
- To investigate the transition-metal-catalyzed cyclization of bissilylethynylated N,N'-dihydrotetraazapentacene (TIPS-TAP-H2).
- To understand the mechanism and selectivity of silyl group migration during the cyclization process.
- To explore the impact of catalyst choice on the reaction outcome and the properties of the resulting cyclopenta[fg,qr]pentacenes.
Main Methods:
- Transition-metal-catalyzed cyclization reactions.
- Control experiments to elucidate reaction pathways.
- Quantum chemical calculations for mechanistic and selectivity analysis.
Main Results:
- Successful synthesis of bissilylated cyclopenta[fg,qr]pentacenes from TIPS-TAP-H2.
- Demonstrated catalyst-dependent silyl group migration (none, one, or two groups).
- Observed similar optoelectronic properties but dramatically different packing motifs in the products.
Conclusions:
- The cyclization reaction offers a route to novel pentacene derivatives with tunable structures.
- Silyl group migration is a key factor controlled by the catalyst, influencing solid-state packing.
- Understanding the reaction mechanism is vital for designing advanced organic materials.
![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
Related Concept Videos
01:18Aromatic Hydrocarbon Cations: Structural Overview
3.2K
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group...
Removing one hydrogen from the intervening CH2 group...
3.2K
01:18Aromatic Hydrocarbon Anions: Structural Overview
3.1K
Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous...
Due to the absence of continuous...
3.1K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.5K
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.
2.5K
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
10.9K
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
10.9K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.1K
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.
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.
2.1K
02:37Disubstituted Cyclohexanes: cis-trans Isomerism
12.9K
Depending upon the different spatial orientation of the substituents, the disubstituted cycloalkanes exhibit two types of stereoisomers. The cis isomers have the substituents on the same side of the ring, whereas the trans isomers have the substituents on the opposite sides. These stereoisomers exhibit different physical properties and cannot be interconverted without breaking the carbon-carbon bonds.
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
12.9K