Triethylamine → 5-Chloro-pyrazine-2-carboxylic acid 2-(tetrahydro-pyran-2-yloxy)-ethyl ester

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Reaction Conditions

Reaction Steps

A solution of 5-chloro-pyrazine-2-carboxylic acid (prepared as in Example 29, 3.15 g, 19.94 mmol) in methylene chloride (50 mL) was treated with 2-(tetrahydropyran-2-yloxy)ethanol (2.91 g, 19.94 mmol). The solution was cooled to 0° C. and then was treated with triethylamine (5.60 mL, 39.88 mmol) and bis(2-oxo-3-oxazolidinyl)phosphinic chloride (5.07 g, 19.94 mmol). The mixture was stirred at 0° C. for 15 min and then at 25° C. for 24 h. The mixture was extracted with methylene chloride and water. The organic layer was washed with a saturated aqueous sodium chloride solution, dried over sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230–400 mesh, 2/1 hexanes/ethyl acetate) afforded 5-chloro-pyrazine-2-carboxylic acid 2-(tetrahydro-pyran-2-yloxy)-ethyl ester as a colorless oil (3.41 g, 60%).

Provenance & Evidence