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Direct Metal-Free Transformation of Alkynes to Nitriles: Computational Evidence for the Precise Reaction Mechanism

Hok, Lucija; Vianello, Robert (2021) Direct Metal-Free Transformation of Alkynes to Nitriles: Computational Evidence for the Precise Reaction Mechanism. International journal of molecular sciences, 22 (6). ISSN 1422-0067

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Abstract

Density functional theory calculations elucidated the precise reaction mechanism for the conversion of diphenylacetylenes into benzonitriles involving the cleavage of the triple C≡C bond, with N-iodosuccinimide (NIS) as an oxidant and trimethylsilyl azide (TMSN3) as a nitrogen donor. The reaction requires six steps with the activation barrier ΔG‡ = 33.5 kcal mol−1 and a highly exergonic reaction free-energy ΔGR = −191.9 kcal mol−1 in MeCN. Reaction profiles agree with several experimental observations, offering evidence for the formation of molecular I2, interpreting the necessity to increase the temperature to finalize the reaction, and revealing thermodynamic aspects allowing higher yields for alkynes with para-electron-donating groups. In addition, the proposed mechanism indicates usefulness of this concept for both internal and terminal alkynes, eliminates the option to replace NIS by its Cl- or Br-analogues, and strongly promotes NaN3 as an alternative to TMSN3. Lastly, our results advise increasing the solvent polarity as another route to advance this metal-free strategy towards more efficient processes.

Item Type: Article
Uncontrolled Keywords: azides ; DFT calculations ; cyanides ; N-iodosuccinimide ; triple C≡C bond cleavage
Subjects: NATURAL SCIENCES > Chemistry
Divisions: Division of Organic Chemistry and Biochemistry
Projects:
Project titleProject leaderProject codeProject type
Inovativna rješenja u katalitičkim proizvodnim procesima za potrebe farmaceutske industrijeKirin, SrećkoKK.01.1.1.04.0013EK
Depositing User: Robert Vianello
Date Deposited: 25 Mar 2021 12:35
Last Modified: 06 Aug 2021 13:20
URI: http://fulir.irb.hr/id/eprint/6369
DOI: 10.3390/ijms22063193

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