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Updated: Jun 3, 2025
A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis
Published on: February 16, 2020
Energy Transfer (EnT)-Mediated Stereoselective Aryl-Heterofunctionalization of Unactivated Alkynes via Radical
Xin-Chao Meng1, Tian-Xiong Pan1, Feng Yang1
1Institute of Materia Medica, School of Pharmaceutical Sciences, Nanjing Tech University, Nanjing 211816, P. R. China.
Abstract:
In this study, we present a novel catalyst-free energy transfer mediated radical rearrangement strategy for the aryl-heterofunctionalization of unactivated alkynes, leading to the synthesis of polyfunctional olefins with exceptional stereoselectivity. This innovative approach, driven by visible light, exemplifies green chemistry principles by eliminating the reliance on transition metals, external oxidants, and photocatalysts. The broad applicability of our method is demonstrated through the successful synthesis of a diverse array of compounds, including vinyl sulfones, vinyl selenides, and vinyl sulfides. Preliminary mechanistic insights suggest an energy transfer mechanism, highlighting the efficiency and selectivity of this novel strategy.
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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.
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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.
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