Sodium Hydroxide → Methyl 4-bromo-3-methylthiophene-2-carboxylate

Temperature

85 °C

A solution of methyl 3-methylthiophene-2-carboxylate (20 g, 103 mmol, 1.0 eq) and sodium hydroxide (12.3 g, 307 mmol, 3 eq) in acetic acid (75 mL) was heated to 60° C. Bromine (46.9 g, 294 mmol, 2.85 eq) was added drop wise at such a rate so as to maintain the temperature of the reaction mixture at <85° C. The resulting mixture was stirred at 85° C. for 6 h. The solution was then allowed to cool to 50° C. and zinc dust (15.4 g, 236 mmol, 2.3 eq) was added in 3 gram portions to the reaction such that the exotherm was controlled to remain below 85° C. The resulting mixture was stirred at 85° C. for 1 h, and then filtered hot through a small bed of celite. Water (300 mL) was added and the mixture was extracted with hexane (300 mL). The organic phase was washed with water, then concentrated to dryness to give 27 g (89%) an off white oil which slowly crystallized upon standing at room temperature. 1HNMR (400 MHz, CDCl3) δ 7.43 (s, 1H), 3.87 (s, 3H), 2.56 (s, 3H)

1. temperatureto maintain the temperature of the reaction mixture at <85° C
2. temperatureto cool to 50° C.
3. customto remain below 85° C
4. stirringThe resulting mixture was stirred at 85° C. for 1 h
5. filtrationfiltered hot through a small bed of celite
6. additionWater (300 mL) was added
7. extractionthe mixture was extracted with hexane (300 mL)
8. washThe organic phase was washed with water
9. concentrationconcentrated to dryness
10. customto give 27 g (89%) an off white oil which
11. customslowly crystallized
12. customupon standing at room temperature

ORD record

ord-87121a73836345ef9be709b3a4951498

Source dataset

uspto-grants-2015_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09169242B2