Sulfuric Acid → (2-Amino-1,3-benzothiazol-5-yl)boronic acid

Participants

Reaction Conditions

Reaction Steps

A solution of Intermediate 75 (459.1 mg) in anhydrous THF (30 ml) was added with N,N,N′,N′-tetramethylethylenediamine (1.51 ml, WAKO), cooled to −78° C. under argon gas atmosphere, then added dropwise with a 1.62 M solution of t-butyllithium in pentane (7.06 ml), and stirred for 30 minutes. The reaction mixture was added dropwise with (iPrO)3B (2.77 ml), stirred for 30 minutes, then warmed to room temperature, and further stirred for 1.5 hours. The reaction mixture was added with 0.5 M aqueous sulfuric acid (7.5 ml) and extracted with diethyl ether (50 ml×3). The organic layer was washed with saturated brine and dried, and then the solvent was evaporated under reduced pressure to obtain crude 2-amino-5-benzothiazoleboronic acid. This compound was reacted with Compound No. A-1 (344 mg), 2 M aqueous sodium carbonate (4.5 ml) and (Ph3P)4Pd (179 mg) and treated according to the procedure described in the synthesis method of Compound No. V-3 with the modifications that the reaction was carried out for 12 hours, and the purification was performed by flash column chromatography (hexane:ethyl acetate=2:1) to obtain the title compound (Compound No. V-77, 76 mg).

Provenance & Evidence