Methyl chloroformate → Methyl 4-bromothiophene-3-carboxylate

A solution of isopropylmagnesium chloride (1.0 g, 9.7 mmol, 1.2 eq.) in THF (5 mL) was added to a solution of 3,4-dibromo-thiophene (2 g, 8.3 mmol, 1.0 eq.) in THF (15 mL), and stirred for 3 hours while the temperature was maintained at 0-5° C. in an ice/salt bath. Methyl chloroformate (1.6 g, 16.9 mmol, 2 eq.) was added dropwise with stirring. The resulting solution was stirred for an additional 16 hours at room temperature. The reaction was then quenched with water (1 mL). The resulting mixture was concentrated under vacuum, then diluted with EtOAc (50 mL). The resulting mixture was washed 1N HCl (1×100 mL) and saturated aqueous NaCl (2×100). The organic layer was concentrated to provide a crude residue, which was applied onto a silica gel column and eluted with EtOAc/PE (1:50) to yield 4-bromothiophene-3-carboxylic acid methyl ester (1.0 g) as a light yellow solid.

1. stirringwith stirring
2. stirringThe resulting solution was stirred for an additional 16 hours at room temperature
3. customThe reaction was then quenched with water (1 mL)
4. concentrationThe resulting mixture was concentrated under vacuum
5. additiondiluted with EtOAc (50 mL)
6. washThe resulting mixture was washed 1N HCl (1×100 mL) and saturated aqueous NaCl (2×100)
7. concentrationThe organic layer was concentrated
8. customto provide a crude residue, which
9. washeluted with EtOAc/PE (1:50)

ORD-Eintrag

ord-c217fb16a7c64c86b4269c269401a79b

Quelldatensatz

uspto-grants-2013_09

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US08530663B2