Chlorotrimethylsilane → (E)-3-cyclopentyl-2-[4-(5-methyl-tetrazol-1-yl)-3-trifluoromethyl-phenyl]-acrylic acid methyl ester

Temperature

25 °C

A mixture of zinc dust (710 mg, 11 mmol, Aldrich, −325 mesh) and dry tetrahydrofuran (1 mL) under argon was treated with 1,2-dibromoethane (187 mg, 1 mmol). The zinc suspension was then heated with a heat gun to ebullition, allowed to cool, and heated again. This process was repeated three times to make sure the zinc dust was activated. The activated zinc dust suspension was then treated with trimethylsilyl chloride (108 mg, 1 mmol), and the suspension was stirred for 15 min at 25° C. The reaction mixture was then treated dropwise with a solution of (E)-3-cyclopentyl-2-iodo-acrylic acid methyl ester (1.54 g, 5.5 mmol) in dry tetrahydrofuran (2 mL) over 3 min. The reaction mixture was then stirred at 40-45° C. for 1 h and then stirred overnight at 25° C. The reaction mixture was then diluted with dry tetrahydrofuran (4 mL), and the stirring was stopped to allow the excess zinc dust to settle down (2 h). In a separate reaction flask, bis(dibenzylideneacetone)palladium(0) (81 mg, 0.15 mmol) and triphenylphosphine (156 mg, 0.6 mmol) in dry tetrahydrofuran (6 mL) was stirred at 25° C. under argon for 10 min and then treated with 1-(4-bromo-2-trifluoromethyl-phenyl)-5-methyl-1H-tetrazole (1.05 g, 3.5 mmol) and the freshly prepared zinc compound in tetrahydrofuran. The resulting brick red solution was heated at 40-45° C. over the weekend. The reaction mixture was cooled to 25° C. and then poured into a saturated aqueous ammonium chloride solution (50 mL), and the organic compound was extracted into ethyl acetate (3×35 mL). The combined organic extracts were washed with a saturated aqueous sodium chloride solution (1×100 mL), dried over anhydrous magnesium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Merck Silica gel 60, 230-400 mesh, 4/1 to 1/1 hexanes/ethyl acetate) afforded (E)-3-cyclopentyl-2-[4-(5-methyl-tetrazol-1-yl)-3-trifluoromethyl-phenyl]-acrylic acid methyl ester (1.03 g, 77.6%) as a light yellow solid: EI-HRMS m/e calcd for C18H19F3N4O2 (M+) 380.1460, found 380.1453.

1. temperatureto cool
2. temperatureheated again
3. stirringThe reaction mixture was then stirred at 40-45° C. for 1 h
4. stirringstirred overnight at 25° C
5. custom(2 h)
6. stirringwas stirred at 25° C. under argon for 10 min
7. temperatureThe resulting brick red solution was heated at 40-45° C. over the weekend
8. temperatureThe reaction mixture was cooled to 25° C.
9. extractionthe organic compound was extracted into ethyl acetate (3×35 mL)
10. washThe combined organic extracts were washed with a saturated aqueous sodium chloride solution (1×100 mL)
11. dry with materialdried over anhydrous magnesium sulfate
12. filtrationfiltered
13. concentrationconcentrated in vacuo

ORD record

ord-4a8926c9fc1c4cd3ab36d200e9a739c7

Source dataset

uspto-grants-2002_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06369232B1