Sodium borohydride → methyl 1-(3,4-dihydro-2H-chromen-6-yl)cyclopropane-1-carboxylate

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Reaction Steps

To trifluoroacetic acid (20 mL) was added NaBH4 (0.70 g, 130 mmol) in portions at 0° C. under N2 atmosphere. After stirring for 5 min, a solution of 1-(4-oxo-chroman-6-yl)-cyclopropanecarboxylic methyl ester (1.6 g, 6.5 mmol) was added at 15° C. The reaction mixture was stirred for 1 h at room temperature before being slowly quenched with water. The resulting mixture was extracted with EtOAc (50 mL×3). The combined organic extracts dried over anhydrous Na2SO4 and evaporated under vacuum to give 1-chroman-6-yl-cyclopropanecarboxylic methyl ester (1.4 g, 92%), which was used directly in the next step. 1H NMR (300 MHz, CDCl3) δ 7.07-7.00 (m, 2H), 6.73 (d, J=8.4 Hz, 1H), 4.17 (t, J=5.1 Hz, 2H), 3.62 (s, 3H), 2.79-2.75 (m, 2H), 2.05-1.96 (m, 2H), 1.57-1.54 (m, 2H), 1.16-1.13 (m, 2H).

Provenance & Evidence