FeCl₃-Catalyzed Tritylation of Alcohols in Ionic Liquids

Abstract

A simple and efficient protection of alcohols as trityl ethers is described using trityl chloride in the presence of 5 mol% FeCl₃ as catalyst in ionic liquids at room temperature in shorter reaction times. This mild and efficient method gives access to the protection of a wide range of alcohols in good yields. The use of ionic liquid allows easy separation of the product and recycling of catalyst.

Keywords:

• Alcohols
• FeCl₃
• ionic liquids
• recyclability
• tritylation

ACKNOWLEDGMENTS

P. R. thanks the director, Indian Institute of Chemical Technology (IICT), Hyderabad, India, for financial support under the project CNP-0222-18. B. N. thanks the Council of Scientific and Industrial Research (CSIR), New Delhi, India, for a research fellowship.

Notes

^a Reaction conditions: catalyst (5 mol%), [bmim]BF₄ (1 mL), p-methyl benzyl alcohol (1 mmol), and trityl chloride (1 mmol) at room temperature.

^b Conversions determined by ¹H NMR.

^c Using [bmim]Cl and [bmim]OTf in place of [bmim]BF₄.

^d Using [bmim]PF₆.

^e CH₂Cl₂ was used as solvent in place of [bmim]BF₄.

^f No reaction in the absence of catalyst.

^a Reaction conditions: catalyst (5 mol%), [bmim]BF₄ (1 mL), p-methyl benzyl alcohol (1 mmol), and tritylchloride (1 mmol) at room temperature.

^b Isolated yield.

^c Isolated yield after fifth cycle.

^d Reaction temperature at 40°C.

^e Two equivalents of trityl chloride.