Abstract

Background: In recent years, the fast-growing development of polymer supported reagents has led to the synthesis of a variety of reagents on solid support. Some of the major advantages of using such reagents are that they are less hygroscopic, easy to recover, and can be recycled.

Objective: The main objective of this study is to develop a mild and simple procedure for iodination of alcohols to their corresponding iodides using polymer supported triphenylphosphine-methylacrylate (PSTTP-MA) complex as catalyst at room temperature.

Method: Polymer supported triphenylphosphine (3 mmol/g; 0.4 mmol, 40 mol%) and methylacrylate (0.034g, 40 mol%) in anhydrous dichloromethane (10 mL) was stirred at room temperature for 2 minutes resulting in the in situ formation of triphenylphosphine-methylacrylate complex. To it was then added iodine (1.5 mmol) and polymer supported triphenylphosphine (1.6 mmol) and the solution was stirred for 5 mins. Finally, alcohol (1 mmol) was added and the reaction was stirred at the same temperature. After complete conversion of the alcohol, the reaction mixture was filtered and washed with dichloromethane. The filtrate was then quenched with an aqueous solution of sodium thiosulfate. The organic layer was separated, dried, filtered and concentrated to get the desired iodide product.

Results: Primary, secondary and tertiary alcohols were smoothly converted into their iodides at room temperature.

Conclusion: Our protocol is high selectivity in favour of benzylic and less substituted alcohols. Use of polymer supported reagents greatly simplifies product isolation requiring only simple filtration and solvent removal in most cases.

Keywords: Bromination, benzylic alcohols, catalysis, iodination, recyclability, solid phase synthesis, selectivity.

Graphical Abstract