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Updated: Jun 7, 2025
Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes
Published on: September 8, 2013
Photoredox-Catalyzed Multicomponent α-Sulfonylation of Terminal Alkynes
Mingyue Zheng1, Xin Zhuang1, Qianfa Jia2
1Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, P. R. China.
This study introduces a new method for creating complex molecules. It uses light to efficiently join simple building blocks, forming valuable compounds with diverse structures.
Area of Science:
- Organic Chemistry
- Photochemistry
- Synthetic Chemistry
Background:
- Sulfonylation reactions are crucial in organic synthesis.
- Developing efficient and selective methods for α-sulfonylation remains a challenge.
Purpose of the Study:
- To explore a generality-oriented and adaptive α-sulfonylation of alkynes.
- To develop a photoinduced multicomponent radical cross-coupling strategy.
Main Methods:
- Utilized terminal alkynes, sulfinates, and alcohols/thiophenols/selenophenols.
- Employed photoinduced radical cross-coupling.
- Investigated mild reaction conditions and functional group tolerance.
Main Results:
- Achieved successful α-sulfonylation of alkynes.
- Demonstrated broad substrate scope and excellent selectivity (chemo-, site-, and stereo-).
- Showcased applicability in late-stage functionalization.
Conclusions:
- Developed a modular platform for synthesizing α-sulfonyl-containing multisubstituted alkenes.
- The protocol offers a versatile approach from simple precursors.
- Highlights the potential for creating value-added, structurally diverse compounds.
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Related Concept Videos
02:27Preparation 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.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.
02:40Alkynes to Aldehydes and Ketones: Acid-Catalyzed Hydration
Analogous to alkenes, alkynes also undergo acid-catalyzed hydration. While the addition of water to an alkene gives an alcohol, hydration of alkynes produces different products such as aldehydes and ketones.
02:34Preparation of Alkynes: Dehydrohalogenation
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.
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
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.
02:42Acidity of 1-Alkynes
The acidic strength of hydrocarbons follows the order: Alkynes > Alkenes > Alkanes. The strength of an acid is commonly expressed in units of pKa — the lower the pKa, the stronger the acid. Among the hydrocarbons, terminal alkynes have lower pKa values and are, therefore, more acidic. For example, the pKa values for ethane, ethene, and acetylene are 51, 44, and 25, respectively, as shown here.