Tunable C-H functionalization and dearomatization enabled by an organic photocatalyst.
Bohang An1, Hao Cui1, Chao Zheng2
1Fujian Key Laboratory of Polymer Materials, Fujian Provincial Key Laboratory of Advanced Materials Oriented Chemical Engineering, College of Chemistry and Materials Science, Fujian Normal University Fuzhou 350007 China zhangxiao@fjnu.edu.cn.
Chemical Science
|March 15, 2024
Summary
A novel photocatalytic strategy enables selective C-H functionalization or dearomatization of aromatic compounds using a single catalyst. This approach offers high yields and selectivity, showcasing the potential of new photocatalysts.
Area of Science:
- Organic Chemistry
- Photocatalysis
- Synthetic Methodology
Background:
- C-H functionalization and dearomatization are key transformations for aromatic compounds.
- Controlling these distinct reaction pathways with a single catalyst remains a significant challenge in synthetic chemistry.
Purpose of the Study:
- To develop a photocatalytic strategy for divergent synthesis of C-H functionalized and dearomatized products from the same precursors.
- To introduce and evaluate a novel photocatalyst for modulating reaction pathways.
Main Methods:
- A photocatalytic system was employed to achieve C-H functionalization under redox-neutral conditions and dearomatization under net-reductive conditions.
- Two sets of indoles and indolines bearing tertiary alcohols were used as substrates.
- Isoazatruxene ITN-2 was utilized as a novel photocatalyst (PC).
Main Results:
- The photocatalytic strategy successfully directed reactions towards either C-H functionalization or dearomatization with high yields and selectivity.
- The novel isoazatruxene ITN-2 photocatalyst demonstrated superior performance compared to conventional photocatalysts.
- Divergent synthesis of functionalized indoles and indolines was achieved.
Conclusions:
- A versatile photocatalytic method was established for controlling C-H functionalization and dearomatization pathways.
- Isoazatruxene-type photocatalysts offer significant advantages and broad application potential due to their efficacy and modifiability.
Related Concept Videos
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.8K
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
Selection Rules: Photochemical Activation
1.8K
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.1K
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.
2.1K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.3K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.3K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.3K
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.
2.3K
01:17Thermal Electrocyclic Reactions: Stereochemistry
2.0K
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.
2.0K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
7.7K
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
7.7K