[OH:1][B:2]1[C:6]2[CH:7]=[C:8]([OH:12])[CH:9]=[C:10]([CH3:11])[C:5]=2[CH:4]([CH2:13][C:14]([O:16][CH2:17][CH3:18])=[O:15])[O:3]1.Br[C:20]1[S:24][C:23]([C:25]#[N:26])=[N:22][N:21]=1.C(=O)([O-])[O-].[K+].[K+]>C(#N)C>[C:25]([C:23]1[S:24][C:20]([O:12][C:8]2[CH:9]=[C:10]([CH3:11])[C:5]3[CH:4]([CH2:13][C:14]([O:16][CH2:17][CH3:18])=[O:15])[O:3][B:2]([OH:1])[C:6]=3[CH:7]=2)=[N:21][N:22]=1)#[N:26]To a mixture of ethyl 2-(1,6-dihydroxy-4-methyl-1,3-dihydrobenzo[c][1,2]oxaborol-3-yl)acetate (1.35 g, 5.4 mmol, 1 eq.) and 5-bromo-1,3,4-thiadiazole-2-carbonitrile (1.54 g, 8.1 mmol, 1.5 eq.) in 50 ml ACN was added potassium carbonate (2.24 g, 16.2 mmol, 3 eq.). The reaction was heated at 60° C. for three hours. The reaction was quenched by water, acidified to pH=3 with 1N HCl and then extracted with EtOAc, washed with brine, dried over Na2SO4, and concentrated under reduced pressure. The crude was purified by column chromatography to give desired product as yellow oil (1.63 g, yield 84%). MS (ESI) m/z=718 [2M+H]+.
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