Trimethyl borate → Boronic acid, (4-ethylphenyl)-

A solution of 1-bromo-4-ethyl benzene (2.0 g, 11 mmol) in dry ether (5 ml) was added to magnesium turnings (311 mg, 13 mmol), which had been suspended in dry ether, by dropwise addition. After addition was complete, the suspension was refluxed for a period of 15 min, by which time nearly all of the magnesium had reacted. The solution was then added to trimethyl borate (1.12 g, 11 mmol), previously dissolved in ether (5 ml) at −78° C., warmed to room temperature and stirred for 90 min. The reaction was quenched by the addition of 10% aqueous HCl (2 ml) and the solution was extracted with ether. The combined ether extract was extracted with 1 M NaOH (2×20 ml), the aqueous extracts were acidified with dilute HCl to pH 2 and extracted with ether (2×25 ml). The resulting combined ether extract was washed once with water (10 ml), dried and evaporated to produce a white solid (676 mg, 38% yield), m.p. 138-140° C.

1. additionAfter addition
2. customhad reacted
3. customThe reaction was quenched by the addition of 10% aqueous HCl (2 ml)
4. extractionthe solution was extracted with ether
5. extractionThe combined ether extract
6. extractionwas extracted with 1 M NaOH (2×20 ml)
7. extractionextracted with ether (2×25 ml)
8. extractionextract
9. washwas washed once with water (10 ml)
10. customdried
11. customevaporated

ORD record

ord-0793ebe8b6504b5787e8fc4239dc9aa4

Source dataset

uspto-grants-2002_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06432994B1