A Selective C-H Deprotonation Strategy to Access Functionalized Arynes by Using Hypervalent Iodine
Sunil K Sundalam1, Aleksandra Nilova1, Thomas L Seidl1
1Department of Chemistry, Portland State University, Portland, OR, 97201, USA.
Angewandte Chemie (International Ed. in English)
|May 31, 2016
Summary
This study presents an efficient method for synthesizing functionalized arynes using aryl(mesityl)iodonium salts. These intermediates are generated via C-H deprotonation and trapped in cycloaddition reactions, offering versatile synthetic applications.
Area of Science:
- Organic Chemistry
- Synthetic Methodology
Background:
- Arynes are highly reactive intermediates crucial in organic synthesis.
- Existing methods for aryne generation often require harsh conditions or specialized precursors.
Purpose of the Study:
- To develop an efficient and versatile method for generating functionalized arynes.
- To explore the scope of aryne cycloaddition reactions with various coupling partners.
Main Methods:
- Preparation of unsymmetrical aryl(mesityl)iodonium tosylate salts in a single pot.
- Ortho-C-H deprotonation of iodonium salts using amide bases.
- Trapping of aryne intermediates via cycloaddition reactions.
Main Results:
- Successful generation and trapping of aryne intermediates.
- Moderate to good yields achieved in cycloaddition reactions with furan.
- Demonstrated utility with other coupling partners like benzyl azide and alicyclic amines.
- Investigated regio- and chemoselectivity, highlighting the role of the spectator aryl ligand.
Conclusions:
- The developed method provides efficient access to functionalized arynes.
- The spectator aryl ligand plays a critical role in controlling reaction selectivity.
- This methodology offers a versatile platform for constructing complex organic molecules.
Related Concept Videos
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
21.8K
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
21.8K
02:34Preparation of Alkynes: Dehydrohalogenation
18.6K
Introduction
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
Alkynes can be prepared by dehydrohalogenation of vicinal or geminal dihalides in the presence of a strong base like sodium amide in liquid ammonia. The reaction proceeds with the loss of two equivalents of hydrogen halide (HX) via two successive E2 elimination reactions.
18.6K
02:27Preparation of Alkynes: Alkylation Reaction
12.5K
Introduction
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.
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.
12.5K
02:38Electrophilic Addition to Alkynes: Halogenation
10.4K
Introduction
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.
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.
10.4K
01:13Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
7.9K
Bromination and chlorination of aromatic rings by electrophilic aromatic substitution reactions are easily achieved, but fluorination and iodination are difficult to achieve. Fluorine is so reactive that its reaction with benzene is difficult to control, resulting in poor yields of monofluoroaromatic products. To address this, Selectfluor reagent is used as a fluorine source in which a fluorine atom is bonded to a positively charged nitrogen.
7.9K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
9.3K
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.
9.3K