Hydrochloric Acid → N-(cis-5,8,11,14-Eicosatetraenoyl)-O-Phospho-L-Serine

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Reaction Steps

A solution of pyridinium cyanoethylphosphate (2 mmol) in anhydrous pyridine (3 ml) was added to dry N-arachidonoyl-L-serine methyl ester. N,N′-Dicyclohexylcarbodiimide (413 mg, 2 mmol) was then added and the mixture was stirred at room temperature. After 20 h, the mixture was cooled to 0° C., water (0.5 ml) was added and, after stirring for 30 min at room temperature, the precipitated N,N′-dicyclohexylurea was separated by filtration. The filtrate was evaporated in vacuo and the residue obtained was fractionated by short column chromatography on silica gel. The desired phosphorylated N-arachidonoyl-L-serine methyl ester was eluted from column with chloroform-methanol (30-40:70-60, v/v). The composition of the eluates was controlled by TLC on Silica gel 60 plates (system B) using a molybdate spray for detecting the spots. The appropriate fractions were combined, evaporated to dryness in vacuo and residue was dissolved in 1 ml tetrahydrofuran. The solution obtained was added, dropwise over a period of 5 min, to a cooled (ice-bath), stirred 1.5 M NaOHaq (4 ml). After a further 25 min, the mixture was acidified with 1 N HCl to pH 2-3 and extracted with chloroform-methanol (70-60:30-40, v/v). The extract was washed with methanol-water (10:9, v/v), concentrated in vacuo and applied to a column of silica gel. The desired product was eluted from column with chloroform-methanol (30-20:70-80, v/v), the fractions containing pure substance stained on the TLC plates with molybdate spray were combined and evaporated to dryness to give 82 mg (35%) of (6): Rf 0.05-0.10 (system B); 1H-NMR (CD3SOCD3, 200 MHz) δ0.9-1.0 (t, 3H, ω-CH3); 1,3 (s, 8H, 4CH2); 2.0-2.4 (m, 6H, 2CH2CH═CH and CH2CO); 2.7-2.9 (br s, 6H, 3HC═CHCH2CH═CH); 3.9-4.0 (br s, 2H, CH2OP); 4.3-4.4 (m, 1H, NHCHCO); 5.2-5.4 (br s, 8H, 4HC═CH); 8.2-8.4 (m, 3H, NH and 2POH)

Provenance & Evidence