Trifluoroacetic acid → palmitoyl-L-Ala-D-Glu(OSu)OBzl

Participants

Reaction Steps

Trifluoroacetic acid (15 ml) was added to Boc-L-Ala-D-Glu-(OH)OBzl (1)(3.26 g) and the mixture was stirred for 20 minutes at room temperature, concentrated in vacuo and washed with diisopropylether. The oil was dissolved in a mixture of water (15 ml) and sodium bicarbonate was added until the pH of the solution became 8-9. The mixture of water (6 ml) and acetone (20 ml) was added to the solution and palmitoyl chloride (2.20 g) was added in one portion. After stirring for 30 minutes at room temperature, the pH of the solution was adjusted to 3 with 1N-hydrochloric acid and the reaction mixture was concentrated. To the residue was added water (30 ml) and the precipitates was collected and dried to give a crude product, which was purified by column chromatography of Silicagel (90 g) with chloroform-methanol (30:1, v/v) as an eluent to give palmitoyl-L-Ala-D-Glu(OH)OBzl (2)(2.00 g). mp. 131°-132° C.

Provenance & Evidence