Regio- and Stereoselective Hydroiodination of Internal Alkynes with Ex Situ-Generated HI

Kanako Nozawa-Kumada*, Koto Noguchi, Tomoya Akada, Masanori Shigeno and Yoshinori Kondo*

*Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan, Email: kanako.kumada.d1tohoku.ac.jp, yoshinori.kondo.a7tohoku.ac.jp

K. Nozawa-Kumada, K. Noguchi, T. Akada, M. Shigeno, Y. Kondo, Org. Lett., 2021, 23, 6659-6663.

DOI: 10.1021/acs.orglett.1c02218

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Abstract

An efficient and practical hydroiodination of internal alkynes using ex situ generated HI provides afford (E)-vinyl iodides in good yields under mild conditions. This regio- and stereoselective hydroiodination reaction shows high functional group tolerance toward alkyl, methoxy, halogen, trifluoromethyl, cyano, ester, halomethyl, acid-sensitive silyl ether, and acetal moieties.

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General Procedure for the Synthesis of Vinyl Iodides

A two-chambered pressure vessel (COware 20 mL, Sigma-Aldrich) with stirring bars was used. Under N₂ atmosphere, chamber B was loaded with alkyne (0.60 mmol) and toluene (1.0 mL) as a solvent. Then, HSiEt₃ (1.2 mmol, 0.19 mL) was loaded to chamber A and the mixture was cooled to −78 °C for 5 min. After the mixture was cooled, I₂ (1.2 mmol, 304.6 mg) was added to chamber A at −78 °C. Then the reaction mixture was stirred at rt for 3 h under dark. The reaction mixture of chamber B was quenched with H₂O and extracted with AcOEt (20 mL × 3). The combined organic layers were washed by 10% Na₂SO₃ aq. (30 mL) and brine (30 mL) and then dried over MgSO₄. The solvent was removed under reduced pressure and the residue was purified by silica gel column chromatography to give the corresponding vinyl iodide.

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Key Words

vinyl iodides

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ID: J54-Y2021