Carbon Dioxide → 3,4-Dihydro-2H-1-benzopyran-8-carboxylic acid

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Reaction Steps

At RT a solution of chroman (17.7 mmol) in ether (15 mL) is added over 10 min to a solution of n-BuLi (19.5 mmol) in a mixture of hexane (12.2 mL) and ether (15 mL). The mixture is stirred at reflux for 150 min, allowed to reach RT and poured into a mixture of dry ice and ether. Ice water is added and the layers are separated. The aq. layer is made acidic and extracted with a mixture of ether and EtOAc. The combined organic layers are washed with water, dried over Na2SO4 and concentrated in vacuo to give a crude product which is purified by CC (heptane/EtOAc 9/1 to EtOAc). LC-MS: tR=0.76 min; [M+CH3CN+H]+=220.1.

Provenance & Evidence