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In a baked-out apparatus filled with argon, magnesium turnings (1.89 g; 78 mmol) were treated with a crystal of iodine and covered with dried THF. Subsequently, a few drops of 4-hexyloxybromobenzene were added to the static solution. The Grignard reaction commenced very quickly and the 4-hexyloxybromobenzene (total amount: 20 g; 78 mmol) was subsequently added dropwise while stirring at such a rate that the mixture boiled gently; during this addition, the mixture was diluted with THF (total of about 100 ml). The mixture was refluxed for 3 hours (only a few flakes of magnesium remaining in the solution) and was subsequently allowed to cool. The Grignard soltuion was transferred in a countercurrent of protective gas to a 250 ml dropping funnel and added dropwise at −70° C. to a solution of trimethyl borate (8.9 g; 9.6 ml; 86 mmol) in 50 ml of dry THF while stirring, with a precipitate being formed. The mixture was allowed to warm to RT overnight and the reaction mixture was poured into a mixture of 100 g of ice and 3 ml of concentrated sulfuric acid while stirring. The organic phase was separated off and the aqueous phase was extracted with 3×100 ml of chloroform, the combined organic phases were evaporated. The crude product was subsequently recrystallized from hexane.

1. customThe Grignard reaction
2. additionduring this addition
3. temperatureto cool
4. stirringwhile stirring, with a precipitate
5. custombeing formed
6. stirringwhile stirring
7. customThe organic phase was separated off
8. extractionthe aqueous phase was extracted with 3×100 ml of chloroform
9. customthe combined organic phases were evaporated
10. customThe crude product was subsequently recrystallized from hexane