Trimethyltin chloride → Methyl 4-(1,1-dimethyl-1-stannaethyl)-5-methylthiothiophene-2-carboxylate

Temperature

-78 °C

4-Bromo-5-methylthiothiophene-2-carboxylic acid (EP 0676395 A2) (4.67 g, 18.4 mmol) was dissolved in anhydrous THF (30 mL), taken in a round bottomed flask and cooled to −78° C. under a N2 atmosphere. To this solution n-butyllithium (20.3 mL, 40.6 mmol, 2M in cyclohexane) was introduced in a dropwise manner. The resulting solution was stirred at −78° C. for 45 min and then allowed to warm up to −60° C. To this solution trimethyltin chloride (40.6 mL, 40.6 mmol, 1M in THF) was added dropwise. This solution was stirred at −60° C. for 30 min and then allowed to warm up to room temperature. The THF was removed under vacuum and the residue was treated with H2O and extracted with hexane. The hexane layer was evaporated and the residue was dissolved in Et2O. The Et2O solution was washed with 10% HCl, saturated NaCl and dried over anhydrous MgSO4. Et2O was removed under vacuum and the residue was taken in MeOH. The MeOH solution was treated with trimethylsilyldiazomethane (18.5 mL, 2M in hexane) and stirred at room temperature for 1 h. The solvents were removed under vacuum to give 2 g (31%) of methyl 4-(1,1-dimethyl-1-stannaethyl)-5-methylthiothiophene-2-carboxylate as an oil. 1H-NMR (CDCl3; 300 MHz) δ0.31 (S, 9H), 2.57 (s, 3H), 3.86 (S, 3H), 6.98 (S, 1H).

1. customtaken in a round bottomed flask
2. temperatureto warm up to −60° C
3. stirringThis solution was stirred at −60° C. for 30 min
4. temperatureto warm up to room temperature
5. customThe THF was removed under vacuum
6. additionthe residue was treated with H2O
7. extractionextracted with hexane
8. customThe hexane layer was evaporated
9. dissolutionthe residue was dissolved in Et2O
10. washThe Et2O solution was washed with 10% HCl, saturated NaCl
11. dry with materialdried over anhydrous MgSO4
12. customEt2O was removed under vacuum
13. additionThe MeOH solution was treated with trimethylsilyldiazomethane (18.5 mL, 2M in hexane)
14. stirringstirred at room temperature for 1 h
15. customThe solvents were removed under vacuum

ORD record

ord-5d00e195b7034e1d9eb753db45cb87c8

Source dataset

uspto-grants-2002_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06492403B1