Imidazole → HCID 15434308, compound

Participants

Reaction Steps

Step a. A solution of 6-hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylic acid methyl ester (i, 41.9 mmol), t-butyl-dimethyl-silyloxy chloride (62.8 mmol), and imidazole (172.2 mmol) in 100 mL of DMF was stirred at 85-95° C. for 16 h, and cooled to room temperature. The solution was diluted with 200 mL of ethyl acetate, washed, in tandem, with H2O, 1% HCl, saturated NaHCO3, and brine, dried with Na2SO4, and concentrated. Purification by flash silica gel chromatography gave the product, 6-(t-butyl-dimethyl-silyloxy)-2,5,7,8-tetramethyl-chroman-2-carboxylic acid methyl ester (ii), as white solid in 99% yield. 1H NMR (300 MHz, CDCl3) δ 0.11 (s, 6H), 1.04 (s, 9H), 1.62 (s, 3H), 1.86-1.76 (m, 1H), 2.01 (s, 3H), 2.11 (s, 3H), 2.16 (s, 3H), 2.22-2.30 (m, 1H), 3.49-3.65 (m, 2H), 3.69 (s, 3H), 4.22 (s, 1H).

Provenance & Evidence