Ethylene Glycol → 2-(4-Bromophenyl)-1,3-dioxolane

Participants

Reaction Steps

This is an example of synthesis of ligand 2. 2-(4′-Dicyclohexylphosphinophenyl)-1,3-dioxolane (Ligand 2): Part I. A solution of 4-bromobenzaldehyde (5 g, 0.027 mol), ethylene glycol (7.0 g, 0.11 mmol), and p-toluenesulfonic acid (0.1 g, 0.5 mmol) in benzene was heated at reflux for 24 h using a Dean-Stark setup to remove water. The reaction was taken up in diethyl ether (100 mL) and washed with water (5×30 mL) and brine (30 mL). The organic phase was dried over magnesium sulfate and concentrated under vacuum to afford 2-(4′-bromophenyl)-1,3-dioxolane (5.95 g). Part II. 2-(4′-bromophenyl)-1,3-dioxolane (1.0 g, 4.4 mmol) was dissolved in anhydrous diethyl ether (30 mL) and the solution was cooled to −78° C. t-Butyllithium (5.14 mL, 1.7 M solution in pentane, 8.8 mmol) was added dropwise with stirring. The reaction was stirred for 2 h at −78 ° C. Chlorodicyclohexylphosphine (1.13 g, 4.8 mmol) was added dropwise via a syringe at −78 ° C. with stirring. The reaction mixture was allowed to warm up to room temperature and stirred for an additional 18 h. To the reaction mixture was added argon purged water (25 mL) slowly. The organic phase was separated under argon and the aqueous phase was washed with diethyl ether (20 mL). The combined organic phase was concentrated under vacuum to afford a colorless oil, which was crystallized from methanol to afford ligand 2 as a white crystalline solid having the structure shown below (yield: 1.4 g, 92%). 31P{1H} NMR (CDCl3): δ2.4.

Provenance & Evidence