Diazomethane → Ethyl 2-(3,5-difluoro-4-hydroxyphenyl)cyclopropanecarboxylate

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Reaction Steps

To a mixture of N-methyl-N′-nitro-N-nitrosoguanidine (TCI-America catalogue # M0527, 10 g on a dry weight basis, 0.068 mol) in ether (150 mL) at 0° C. was added a cold solution of potassium hydroxide (12.60 g) in water (21 mL). After stirring for 2 minutes, a portion of the yellow ethereal solution of the resulting diazomethane was added to a solution of ethyl 3-(3,5-difluoro-4-hydroxyphenyl)acrylate (10) (2.28 g, 0.010 mol) in ether (100 mL) at 0° C. A portion of palladium (II) acetate (0.372 g, 1.66 mmol) was added followed by an additional portion of diazomethane solution. This process was continued until all the diazomethane solution and palladium (II) acetate was added. The resulting dark mixture was stirred at 0-5° C. for 4 hours and acetic acid (6 drops) was added to quench any excess reagent. After removal of solvent in vacuo, the residue was purified by chromatography on silica gel (0-30% EtOAc in hexanes) to afford the desired product (12) as a white solid. 1H NMR (400 MHz, CDCl3) δ: 6.67 (d, J=8.4 Hz, 2H), 5.05 (br, 1H), 4.20 (q, J=7.1 Hz, 2H), 2.45-2.40 (m, 1H), 1.87-1.74 (m, 1H), 1.39-1.14 (m, 5H).

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