FeCl₃-Mediated Reaction of Alkynols with Iodine: An Efficient and Convenient Synthetic Route to Vinyl Iodides

Abstract

The FeCl₃-mediated reaction of alkynols with iodine resulted in intramolecular addition of hydroxyl to alkyne to produce a wide range of iodocycloenol ethers in good to excellent yields under mild reaction conditions. On the other hand, 1,2-diiodides were obtained in good yields when propargyl alcohol reacted with iodine in the same condition.

Keywords:

• Intramolecular iodoetherification
• iron trichloride
• vinyl iodide

ACKNOWLEDGMENTS

The authors are grateful to the NSF of China (20772099) and Natural Science Foundation of Jiangxi Province (2009GZH00013) for financial support.

Notes

^a Reactions were conducted with catalyst (0.3 mmol), 5-hexyn-1-ol (1.0 mmol), and iodine (1.0 mmol) in CH₃CN (5 mL) at rt.

^b Isolated yield.

^c Reaction was conducted with 5-hexyn-1-ol (1.0 mmol) and iodine (1.5 mmol) in CH₃CN (5 mL) at rt.

^d (E)-2a was isolated as a single diastereomerm, and the E-conformer was confirmed by NOESY experiment.

^e 0.2 mol equiv FeCl₃ · 6H₂O was used.

^f 1.0 mol equiv FeCl₃ · 6H₂O and 0.5 mol equiv I₂ were used.

^a All reactions were conducted with FeCl₃ · 6H₂O (1.0 mmol), alkynol (1.0 mmol), and iodine (0.5 mmol) in CH₃CN (5 mL) at rt.

^b Isolated yield.

^c Not detected and 4-phenyl pent-3-en-1-yne was obtained with 15% yield because the reaction was messy.

^d 2b was isolated as a single diastereomer and was expected to be E-conformer by the reaction mechanism (Scheme 2).

^e Ratio determined by ¹H NMR analysis.