Trimethylboroxine → Methyl 3,4-dimethylthiophene-2-carboxylate

A solution of methyl 3-iodo-4-methylthiophene-2-carboxylate (400 mg, 1.418 mmol), trimethylboroxine (793 μL, 5.67 mmol) and 1,1′-bis(di-tert-butylphosphino)ferrocene palladium dichloride (92 mg, 0.142 mmol) in THF (2363 μL) was degassed by bubbling N2 through the solution. 1N aq. K2CO3 (2363 μL) was added and N2 was bubbled through the mixture for 30 s. The mixture was subjected to microwave irradiation in a sealed tube at 120° C. for 30 min. The reaction mixture was filtered through a plug of silica, eluted with EtOAc and the filtrate was washed with 1N aq. NaOH (2×), dried (Na2SO4) and concentrated in vacuo to afford the crude product. This was purified by flash chromatography (Biotage Horizon, 25M, Si, ˜20 mL/min, 100% hexanes for 144 mL, gradient to 10% EtOAc in hexanes over 1140 mL) to afford methyl 3,4-dimethylthiophene-2-carboxylate.

1. customby bubbling N2 through the solution
2. addition1N aq. K2CO3 (2363 μL) was added
3. customN2 was bubbled through the mixture for 30 s
4. customirradiation in a sealed tube at 120° C. for 30 min
5. filtrationThe reaction mixture was filtered through a plug of silica
6. washeluted with EtOAc
7. washthe filtrate was washed with 1N aq. NaOH (2×)
8. dry with materialdried (Na2SO4)
9. concentrationconcentrated in vacuo
10. customto afford the crude product
11. customThis was purified by flash chromatography (Biotage Horizon, 25M, Si, ˜20 mL/min, 100% hexanes for 144 mL, gradient to 10% EtOAc in hexanes over 1140 mL)

ORD record

ord-9a508379d25c400b817c7fd3f07e4f5e

Source dataset

uspto-grants-2015_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09221834B2