Reaction #1596944

Reaction equation

ethanol

bismuth(III) bromide

4-benzyloxy-3-fluorobenzaldehyde

2-vinylpentan-1-ol

→

2-(4-benzyloxy-3-fluorophenyl)-4-bromo-5-propyltetrahydropyran

Solvents

chlorobutane

dichloromethane

Conditions

Workup

1. 1
   OtherInsoluble constituents are separated off
2. 2
   Filtrationthe mixture is filtered absorptively (SiO2, CH2Cl2)
3. 3
   ConcentrationThe filtrate is concentrated to dryness
4. 4
   Otherthe residue is purified by column chromatography (SiO2, n-heptane:MTBE=4:1)
5. 5
   OtherThe oil obtained
6. 6
   OtherThe crystals which deposit are collected
7. 7
   Otherrecrystallised again from n-heptane

Procedure

188.0 g (0.79 mol) of 4-benzyloxy-3-fluorobenzaldehyde are initially introduced in 1000 ml of dichloromethane at 0° C. together with 90.0 g (0.79 mol) of 2-vinylpentan-1-ol. 176.0 g (0.39 mol) of bismuth(III) bromide are added in portions, and the mixture is stirred at room temperature for 19 h. Insoluble constituents are separated off, and the mixture is filtered absorptively (SiO2, CH2Cl2). The filtrate is concentrated to dryness, and the residue is purified by column chromatography (SiO2, n-heptane:MTBE=4:1). The oil obtained is taken up in chlorobutane, and the solution is added dropwise to cold ethanol. The crystals which deposit are collected and recrystallised again from n-heptane. In this way, 2-(4-benzyloxy-3-fluorophenyl)-4-bromo-5-propyltetrahydropyran is obtained as a yellowish solid.

Source