Iodine → 7,8-Difluoro-5-iodo-6-methoxymethoxychroman

HRID 2244831Notes

Reaction equation

[F:1][C:2]1[C:11]([F:12])=[C:10]2[C:5]([CH2:6][CH2:7][CH2:8][O:9]2)=[CH:4][C:3]=1[O:13][CH2:14][O:15][CH3:16].[Li]CCCC.[I:22]I>C1COCC1.CC(OC)(C)C>[F:1][C:2]1[C:11]([F:12])=[C:10]2[C:5]([CH2:6][CH2:7][CH2:8][O:9]2)=[C:4]([I:22])[C:3]=1[O:13][CH2:14][O:15][CH3:16]

Participants

Conditions

Temperature: 20 °C

Procedure

16.6 g (72.1 mmol) of 7,8-difluoro-6-methoxymethoxychroman are initially introduced in 350 ml of THF, and 54.3 ml (86.5 mmol) of n-BuLi (15% soln. in hexane) are added dropwise at −78° C. When the addition is complete, the mixture is stirred at this temperature for 30 min and subsequently at 20° C. for 1 h. The solution is re-cooled to −78° C., and a solution of 22.0 g (86.5 mol) of iodine in 100 ml of THF is added dropwise. The reaction mixture is stirred at room temperature for 1.5 h and subsequently diluted with MTBE. The solution is washed with water and sat. sodium chloride soln. and dried using sodium sulfate. The crude product remaining after removal of the solvents is purified by column chromatography (SiO2, n-heptane:MTBE=2:1), giving 7,8-difluoro-5-iodo-6-methoxymethoxychroman as a brownish oil.

Workup

additionWhen the addition
temperatureThe solution is re-cooled to −78° C.
stirringThe reaction mixture is stirred at room temperature for 1.5 h
washThe solution is washed with water and sat. sodium chloride soln
customand dried
customafter removal of the solvents
customis purified by column chromatography (SiO2, n-heptane:MTBE=2:1)

Sources & evidence

ORD record: ord-eb4fe2155ff2426ebb4ccdd6435b6073
Source dataset: uspto-grants-2010_03
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07678929B2

Reaction notes

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