Triphenylphosphine → (E)-2-[4-Cyclopentyl-2-(4-methanesulfonyl-phenyl)-but-2-enoylamino]-thiazole-5-carboxylic acid ethyl ester

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of triphenylphosphine (787 mg, 3 mmol) in methylene chloride (40 mL) was cooled to 0° C. and then treated with N-bromosuccinimide (534 mg, 3 mmol). The reaction mixture was stirred at 0° C. for 30 min and then treated with (E)-4-cyclopentyl-2-(4-methanesulfonyl-phenyl)-but-2-enoic acid (prepared in Example 21, 462 mg, 1.5 mmol). The clear solution was stirred for 10 min at 0° C. and then allowed to warm to 25° C. where it was stirred for 1 h. The reaction mixture was then treated with 2-aminothiazole-5-carboxylic acid ethyl ester (774 mg, 4.5 mmol), and the resulting suspension was stirred at 25° C. over the weekend. The reaction mixture was concentrated in vacuo to remove methylene chloride, and the residue was diluted with ethyl acetate (70 mL) and a 1N aqueous hydrochloric acid solution (70 mL). The two layers were separated, and the aqueous layer was extracted with ethyl acetate (1×50 mL). The combined organic extracts were successively washed with a saturated aqueous sodium bicarbonate solution (1×100 mL) and a saturated aqueous sodium chloride solution (1×100 mL), dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. Biotage chromatography (FLASH 40M, Silica, 3/1 to 1/1 hexanes/ethyl acetate) afforded (E)-2-[4-Cyclopentyl-2-(4-methanesulfonyl-phenyl)-but-2-enoylamino]-thiazole-5-carboxylic acid ethyl ester (250 mg, 36%) as an amorphous white solid: ET-HRMS m/e calcd for C22H26N2O5S2 (M+) 462.1283, found 462.1282.

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