To a solution of 6-[(isoquinoline-1-carbonyl)-amino]-2-(2-nitro-benzenesulfonyl)-5-oxo-1,3,4,5,6,7,10,10a-octahydro-2H-2,4a-diaza-benzocyclooctene-4-carboxylic acid methyl ester (1.5 g, 2.53 mmol) in DMF (55 mL) is added 4-mercaptophenol (1.28 g, 10.1 mmol) and K2CO3 (1.4 g, 10.1 mmol). The solution is stirred at rt for 12 hrs, diluted with EtOAc, washed with water and brine, dried (MgSO4), filtered, and concentrated. The crude residue is purified by preparative reverse phase HPLC (CH3CN/H2O with 0.1% TFA) to yield 1.16 g of product as a TFA salt.
