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

反応式

[O:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH2:4][CH2:3][CH2:2]1.[Li]CCCC.[C:16](=[O:18])=[O:17]>CCOCC.CCCCCC>[O:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][C:9]=2[C:16]([OH:18])=[O:17])[CH2:4][CH2:3][CH2:2]1

参加物

実験手順

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.