The stereo-divergent functionalization of alkynes: a comprehensive review
Ranjay Shaw1, Ashmita Singh2, Ismail Althagafi3
1Department of Chemistry, GLA University Mathura 281406 India.
Abstract:
Alkynes are central in crafting pharmaceuticals, agrochemicals, and materials owing to their reactivity and linear geometry. This review unveils cutting-edge advancements in the stereo-divergent functionalization of alkynes, transforming them into invaluable tools for synthesizing stereochemically defined alkenes and alkanes. The review highlights ground-breaking methodologies that achieve exceptional E- and Z-selectivity using innovative catalysts like cobalt, nickel, and palladium through hydrogenation, hydroboration, and hydrosilylation. Recent breakthroughs such as dual-catalytic systems and energy transfer catalysis enable unprecedented stereocontrol. Sustainable strategies including water as a hydrogen source and recyclable catalysts align with green chemistry principles, paving the way for eco-friendly synthesis. This synthesis of cutting-edge techniques and their applications inspire new avenues in synthetic chemistry, offering transformative tools for creating complex molecular architectures with precision and sustainability.
More Related Videos
06:46Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
09:35Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
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.
02:24Reduction 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.
02:38Electrophilic 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.
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.
02:47Alkynes 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.
01:28Diels–Alder Reaction Forming Cyclic Products: Stereochemistry