preparation of 5-bromo-2-ethoxypyridine-4-boronic acid_industrial additives

preparation background and overview of 5-bromo-2-ethoxypyridine-4-boronic acid

5-bromo-2-ethoxypyridine-4-boronic acid is an organic intermediate that can be used in suzuki and other coupling formaldehyde-furan reactions. it is mainly used in laboratory research and development processes and chemical and pharmaceutical synthesis processes.

preparation of 5-bromo-2-ethoxypyridine-4-boronic acid

general/typical procedure: the synthesis of 5-bromo-2-ethoxypyridine-4-boronic acid refers to 3-bromo-6-methoxy-4-pyridylboronic acid, except that 5-bromo- 2-methoxypyridine was replaced with 5-bromo-2-ethoxypyridine. the synthesis of 3-bromo-6-methoxy-4-pyridylboronic acid is as follows:

to a solution of 5-bromo-2-methoxypyridine (9) (727 mg, 3.9 mmol) in anhydrous thf (10 ml) at -78°c, lda (2.0 m, in heptane-thf) was added dropwise -ethylbenzene, 2.0 ml, 4.0 mmol). the reaction mixture was stirred at -78 °c for 1 h, then tipb (1.5 g, 7.8 mmol) was added dropwise. the mixture was stirred at -78°c for 1 hour, then quenched with h₂o (10 ml) and allowed to warm to 20°c overnight. the reaction solution was post-treated (then the aqueous layer was acidified to ph 4 with 48% hbr aqueous solution to precipitate) to obtain the product 3-bromo-6-methoxy-4-pyridylboronic acid.

the synthesis of 5-bromo-2-ethoxypyridine-4-boronic acid is based on the above method. the raw materials are as follows: 5-bromo-2-ethoxypyridine (10) (261 mg, 1.3 mmol), thf (10 ml) ) and lda (2.0 m heptane-thf-ethylbenzene, 0.8 ml, 1.5 mmol) solution. the product was a white solid (74 mg, 23%). melting point 103-105℃.

¹h nmr [(cd₃)₂co]-tms]: &delta tetramethylurea tetrafluoroborate; = 8.15 (s, 1h), 7.70 (s, 2h, oh), 6.81 (s, 1h), 4.30 (q, 2h, j = 7.2hz), 1.32 (t, 3h, j = 6.8hz).

¹³c nmr [(cd₃)₂c(o)-tms]: δ= 162.48,147.45,115.86,114.67 ,61.72,14.15 anal.

calculated for c7h9bbrno3 (245.9): c, 34.20; h, 3.69; n, 5.70. measured values: c, 34.90; h, 3.25; n, 5.90.