Hydrochloric Acid → HCID 59134901, compound

Participants

Reaction Conditions

Reaction Steps

n-Butyllithium (7.9 mL of a 2.5 M solution in hexanes, 20 mmol) was added to a solution of compound 2b (4.7 g, 20 mmol) in 100 mL THF at −78° C. The mixture was allowed to warm to −25° C. over 1 hr, then the mixture was cooled to −78° C. Trimethylborate (3.4 mL, 30 mmol) was added and the reaction was allowed to warm to RT. Hydrochloric acid (1N, 100 mL) was then added and the mixture was stirred for 16 hr. The pH of the aqueous layer was adjusted to 3-4 using sodium hydroxide and sodium dihydrogen phosphate solution, then the mixture was extracted with ethyl acetate. The organic layer was concentrated, then the residue was partitioned between ether and 0.5 N sodium hydroxide solution. The aqueous layer was extracted with two additional portions of ether and was then acidified to pH 3-4 using concentrated hydrochloric acid. The mixture was extracted with ethyl acetate, and the combined ethyl acetate extracts were dried over sodium sulfate, filtered, and evaporated to afford 2-methyl-4-(pyrazol-1-yl)phenylboronic acid (compound 2c, 3.5 g) as an amber gum.

Provenance & Evidence