To 2-{2-[2-(2-mercapto-ethoxy)-ethoxy]-ethoxy}-ethanol (310 mg, 1.47 mmol) and trityl chloride (452 mg, 1.62 mmol, 1.1 eq.) in a round bottomed flask was added simultaneously triethylamine (2.1 ml, 10 eq.) and THF (25 ml) under argon. The initial red colour faded upon stirring at ambient temperature for 1 hour. The reaction was monitored by TLC, ethyl acetate/ethanol (1:1) and was completed after 6 hours. Thereafter methanol (6 ml) was added to consume excess trityl chloride and the mixture stirred for 5 minutes before evaporation of the solvents. The residue was purified by flash chromatography using 100% ethyl acetate to afford the product (550 mg, 83%) as a colourless oil.
