Phthalimide (Sigma-Aldrich), Triphenylphosphine (PPh3) (Sigma-Aldrich), absolute Tetrahydrofuran (THF) (Sigma), Triethylene glycol monomethyl ether (Fluka), Diisopropyl azodicarboxylate (DIAD) (Fluka), Petroleum ether (Fluka), Ethanol (Fluka), Dichlormethane (Fluka)

Phthalimide (3.60 g, 24.5 mmol, 1.2 eq.) and PPh3 (6.42 g, 24.5 mmol, 1.2 eq) were placed under argon in a 2-neck-flask, and dissolved in absolute THF (100 ml). The solution was treated with triethylene glycol monomethyl ether (3.2 ml, 20.4 mmol, 1.0 eq.). After 15 min, DIAD (4.73 ml, 24.5 mmol, 1.2 eq.) was added dropwise at rt., resulting in a slight warming of the solution. After 12 h at rt., TLC showed that the reaction was complete (Hexan-EtOAc/1:1, product Rf 0.31, start material Rf 0.1). The reaction was quenched by addition of EtOH (40 ml). The solvent was evaporated in vacuo and the residue dried at 1 mbar and 40°C for 1 h. The residue was treated with 20 ml petroleum ether (PE)-EtOAc (1 : 1) and stirred at 40°C for 1 h. The white residue was filtered off and washed with 10 ml PE-EtOAc (1 : 1). The filtrate was evaporated to dryness, dried at high vacuum, dissolved in 1 ml dichlormethane and chromatographed on silica gel (10-50% EtOAc in hexane). In this way, the title compound was synthesised as a colorless oil (4.73 g, 16.1 mmol, 79 %).

TLC (Hexan-EtOAc/1:1): Rf = 0.31. 1H NMR (CDCl3, 400 MHz): 7.80 (dd, J = 3.0 Hz, J = 5.5 Hz, 2H), 7.68 (dd, J = 3.0 Hz, J = 5.5 Hz, 2 H), 3.87 (t, J = 5.8 Hz, 2 H), 3.71 (t, J = 5.8 Hz, 2 H), 3.64 – 3.54 (m, 6 H), 3.45 – 3.42 (m, 2 H), 3.30 (s, 3 H). 13C-NMR (CDCl3, 125 MHz): 168.12, 133.79, 132.01, 123.09, 71.75, 70.44, 70.41, 69.99, 67.79, 58.87, 37.15.

Synthesis (6), 816-824, 2002.