One-Pot Wittig Reactions in Water and in the Presence of a Surfactant

Abstract

α,β-Unsaturated esters were synthesized in open atmosphere via mild and efficient one-pot Wittig reactions performed in both water and sodium dodecyl sulfate (SDS)-water solution.

Key words

alkenes - esters - Wittig reaction - micelles

References and Notes

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10

Phosphonium dodecylsulfate was isolated from a blank reaction performed as reported below in the absence of the base and of the electrophile: ethyl α-bromo acetate (0.5 mmol) was added, under stirring, to a solution of SDS (0.05 g) in H₂O (0.5 mL), followed by the addition of tri-n-butylphosphine (0.5 mmol). The reaction mixture was poured in EtOAc (10 mL); Na₂SO₄ was added under stirring to remove H₂O, filtered and washed with EtOAc (3 × 5 mL). The organic solvent was removed under reduced pressure. The residue was washed with n-hexane, dried, and dissolved in CDCl₃: ¹H NMR (CDCl₃): δ = 0.86 (3 H, t, J = 7.0 Hz), 0.96 (9 H, t, J = 6.8 Hz), 1.20-1.23 (16 H, m), 1.31 (3 H, t, J = 6.8 Hz), 1.30-1.45 (2 H, m), 1.45-1.55 (12 H, m), 1.55-1.70 (2 H, m), 2.40-2.50 (6 H, m), 3.79 (2 H, d, J = 13.2 Hz), 4.01 (2 H, t, J = 7.5 Hz), 4.20 (2 H, q, J = 6.8 Hz).

11

All products were isolated by flash chromatography. Their purity, structure and stereoisomeric ratios (when E/Z mixtures were obtained) were determined by ¹H NMR analysis, in comparison with the literature data.