反应详情

To a suspension of magnesium turnings (33 g) in dry THF (150 mL) was added 2-bromotoluene (4 mL). The reaction mixture was heated to reflux and an exotermic reaction started. The heating mantle was removed and 2-bromotoluene (137 mL) in dry THF (500 mL) was added dropwise over an hour at reflux temperature (exotermic reaction). The resulting reaction mixture was boiled under reflux for additionally 1.5 hrs. The mixture was cooled to room temperature and excess Mg was filtered off in an inert atmosphere. A solution of 4-chlorobutyric acid methylester (56.4 g) in dry THF (200 mL) was added dropwise at 20° C. The reaction mixture was stirred at room temperature for additionally 1 hr and was then poured into an aqueous solution of NH4Cl and ice. The organic phase was worked-up according to the standard workup procedures. After evaporation of the organic solvent the residue was suspended in a mixture of n-heptane/ethyl acetate=4/1. Filtration of the resulting crystals afforded 2,2-di-(2-tolyl)-tetrahydrofuran 33a (32.5 g). 1H NMR (CDCl3) δ 1.96 (s,6H), 1.96-2.10 (m,2H), 2.57 (t,2H), 4.02 (t,2H), 7.00-7.07 (m,2H), 7.07-7.23 (m,4H), 7.57-7.65 (m,2H)

1. temperatureThe reaction mixture was heated
2. temperatureto reflux
3. customan exotermic reaction
4. customThe heating mantle was removed
5. addition2-bromotoluene (137 mL) in dry THF (500 mL) was added dropwise over an hour
6. temperatureat reflux
7. customtemperature (exotermic reaction)
8. customThe resulting reaction mixture
9. temperatureunder reflux for additionally 1.5 hrs
10. filtrationexcess Mg was filtered off in an inert atmosphere
11. additionA solution of 4-chlorobutyric acid methylester (56.4 g) in dry THF (200 mL) was added dropwise at 20° C
12. additionwas then poured into an aqueous solution of NH4Cl and ice
13. customAfter evaporation of the organic solvent the residue
14. additionwas suspended in a mixture of n-heptane/ethyl acetate=4/1
15. filtrationFiltration of the resulting crystals