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Updated: Jan 11, 2026

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units
Published on: September 18, 2016
From Straight Lines to Loops: Alkyne Magic in Heterocycle Synthesis
Santosh J Gharpure1, Juhi Pal1, Shipra Somani1
1Department of Chemistry, Indian Institute of Technology Bombay, Powai, Maharastra, 400076, India.
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Alkyne is one of the simplest yet important functional group in organic synthesis. The richness of this entity renders it as an extremely versatile synthon for developing a diverse array of modern strategies for assembly of different heterocycles. This account describes the research efforts of more than a decade on the usage of alkynes as nucleophiles, electrophiles, and radical precursors for the synthesis of diverse set of heterocycles and the utilization in the total synthesis of structurally simple to complex bioactive natural products.
Related Concept Videos
Preparation 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.
Nomenclature of Alkynes
Preparation 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.
Electrophilic 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.
Alkynes 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.
Cycloaddition Reactions: Overview
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