Diethyl Ether → 6-Bromo-2,2,4,4-tetramethyl chroman-8-carbaldehyde

反応式

[Br:1][C:2]1[CH:3]=[C:4]2[C:9](=[CH:10][CH:11]=1)[O:8][C:7]([CH3:13])([CH3:12])[CH2:6][C:5]2([CH3:15])[CH3:14].[CH2:16]([O:18]CC)C>ClCCl.[Ti](Cl)(Cl)(Cl)Cl>[Br:1][C:2]1[CH:3]=[C:4]2[C:9](=[C:10]([CH:16]=[O:18])[CH:11]=1)[O:8][C:7]([CH3:13])([CH3:12])[CH2:6][C:5]2([CH3:15])[CH3:14]

参加物

実験手順

A stirred, cooled (ice bath) solution of 6-bromo-2,2,4,4-tetramethyl chroman, (0.5 g, 1.865 mmol) in anhydrous dichloromethane (5 mL) was treated with a 1M solution (1.86 mL, 1.86 mmol) of titanium tetrachloride in dichloromethane followed by α,α-dichloro methyl ether (0.214 g, 1.865 mmol). The reaction mixture was allowed to warm to ambient temperature for 4 h. The reaction mixture was diluted with diethyl ether, washed with brine (×1) and dried over anhydrous sodium sulfate, filtered and evaporated in vacuo to a residue which was subjected to flash column chromatography over silica gel (230-400 mesh) using 5% ethyl acetate in hexane to afford the title compound as a yellow solid (0.52 g, 94%).