preparation of 2,5-dibromophenylboronic acid pinacol ester_industrial additives

preparation background and overview of 2,5-dibromophenylboronic acid pinacol ester

2,5-dibromobenzene pinacol ester is an organic intermediate, which can be prepared in one step from 2,5-dibromobenzene and diboron pinacol ester. 2,5-dibromophenylboronic acid pinacol ester can be used in suzuki and other coupling reactions.

preparation of 2,5-dibromophenylboronic acid pinacol ester

preparation method 1 of 2,5-dibromophenylboronic acid pinacol ester,

2,5-dibromophenylboronic acid pinacol ester is compound 5ac in the picture below.

a dry schlenk flask (15 ml volume) equipped with a stir bar was charged with pinacol diborate (126.9 mg, 0.5 mmol, 1.0 eq), [ir(ome)(cod)] ₂ (3.4 mg, 0.005 mmol, 1.0 mol%), ligand (4.0 mg, 0.005 mmol, 2.0 mol%) and 1,4-dibromobenzene (118.0 mg, 0.5 mmol). evacuate and replenish 3 times with dry nitrogen. stir at 100°c for 16 hours, filter, spin the filtrate to dryness and perform column chromatography to obtain 2,5-dibromophenylboronic acid pinacol ester.

preparation method 2 of 2,5-dibromophenylboronic acid pinacol ester,

qiu d et al. reported that 2,5-dibromophenylboronic acid pinacol ester can be prepared from phenylboronic acid pinacol ester through two consecutive bromination steps. a single bromination operation is as follows: in a 25 ml flask, weigh pinacol phenylborate (1 mmol), nbs (178 mg, 1 mmol), aucl₃ (3 mg, 1 mmol% ), then add dce (2 ml). the reaction was stirred at room temperature for 6 hours. the solution was then concentrated by rotary evaporation to give a crude residue, which was purified by silica gel column chromatography to give the product.

references

[1] wang g , xu l , li p . double n,b-type bidentate boryl ligands enabling a highly active iridium catalyst for c-h borylation[j]. journal of the american chemical society, 2016, 46(25) :8058-61.

[2] qiu d , mo f , zheng z , et al. gold(iii)-catalyzed halogenation of aromatic propyl carbonate borona aluminum magnesium carbonatetes with n-halosuccinimides.[j]. organic letters, 2015, 42 (12):5474-7.