Carbon Dioxide → 2,3-Dihydro-5-methyl-7-benzofurancarboxylic acid

Participants

Reaction Steps

To a stirred solution of 2-(2,6-dibromo-4-methylphenyloxy)ethyl bromide (19) (5.82 g, 15.6 mmol) in dry THF (90 ml) and hexane (30 ml) under argon there was added 7.8 ml of n-BuLi (2.5M in hexane) at -78° C. (dry ice/acetone bath). After 30 minutes at -78° C., an additional 7.8 ml of n-BuLi was added. After an additional 1 hour stirring, the light yellow reaction solution was poured into a slurry of dry ice (prewashed with dry ether). After the mixture had come to room temperature, the precipitated white solid was collected on a filter, treated with 1N HCl to adjust the pH of the supernatant liquid to 1. The mixture was cooled briefly in the freezer, and the solid collected on a filter to afford 2.52 g (90.7%) of acid 20. The crude product was recrystallized from CH3OH/H2O to yield 1.70 g (61.2%) of 20 as a white solid, mp 177°-179° C. IR(KBr) 3420 (OH) and 1680(C=0) cm-1. NMR(CDCl3) δ 8.47 (br s, 1H, OH), 7.50 (s, 1H, aromatic proton), 7.15 (s, 1H, aromatic proton), 4.70 (t, 2H, J=9 Hz, OCH2), 3.20 (t, 2H, OCH2CH2), and 2.32 (s, 3H, CH3).

Provenance & Evidence