Phosphorus oxybromide → HCID 136343979, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of the mixture of 4,7-dihydroxy-3-methyl-isothiazolo[5,4-c]pyridine-5-carboxylic acid butyl ester and 4,7-dihydroxy-3-methyl-isothiazolo[4,5-c]pyridine-6-carboxylic acid butyl ester (6.67 mmol) obtained as described above in dichloroethane (33.3 mL) was added POBr3 (8.0 mmol). The reaction mixture was stirred at 120° C. in a microwave oven for 35 min. After cooling to r.t., the mixture was partitioned between CH2Cl2 and sat. NaHCO3, then filtered and the organic layer of the filtrate was washed with brine before it was dried over MgSO4 and concentrated in vacuo. The residue was purified by flash column chromatography on silica gel. Eluting with 0-20% EtOAc/CH2Cl2, gave 7-bromo-4-hydroxy-3-methyl-isothiazolo[5,4-c]pyridine-5-carboxylic acid butyl ester (850 mg) as a white solid: MS (m/z) 342.9 (M−1), 345.0 (M−1), and 4-Bromo-7-hydroxy-3-methyl-isothiazolo[4,5-c]pyridine-6-carboxylic acid butyl ester (473 mg) as a white solid: MS (m/z) 342.9 (M−1), 345.0 (M−1).

Provenance & Evidence