11-Bromoundecanoic acid → Undecanoic acid, 11-chloro-

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Reaction Steps

To 11-bromoundecanoic acid (1 g) dissolved in acetonitrile (50 ml) were added calcium chloride (2 g) and tetra-n-butylammonium chloride (1.2 g), and the mixture was heated under reflux for 4 hours. The reaction mixture was filtered, concentrated and then distributed into ethyl acetate-water, and the ethyl acetate layer was dried over anhydrous sodium sulfate to give 11-chloroundecanoic acid (0.85 g). After a 230 mg portion of 11-bromoundecanoic acid thus obtained, para-nitrophenol (145 mg) and N,N'-dicyclohexylcarbodiimide (215 mg) in N,N-dimethylformamide (DMF) was stirred for 12 hours, precipitates were removed by filtration and DMF was removed by distillation to give an active ester. To the active ester of 11-chloroundecanoic acid dissolved in DMF (20 ml) were added 6-(4'-N-glycyl-spicaminyl-amino)purine hydrochloride (400 mg) and triethylamine (1.2 ml), and the mixture was stirred for 12 hours. The reaction mixture was concentrated and subjected to chromatography on a silica gel column with eluent systems of chloroform-methanol (from 7:1 to 5:1) to give SPK133 in the yield of 103 mg.

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