To a solution of 3-[[(1,1′-biphenyl)-4-yl]sulfonyl]amino-2-oxo-5-[(phenylthio)methyl]-tetrahydrofuran 16c (0.18 g, 0.41 mmol) in water (5 mL) and THF (5 mL) is added slowly lithium hydroxide monohydrate (172 mg, 4.1 mmol). The reaction mixture is stirred for 3 hr, then concentrated to dryness. The resulting mixture is diluted with water, and then the mixture is extracted twice with Et2O. The Et2O layer is discarded and the aqueous layer is neutralized carefully with 1N HCl to pH 6, then extracted three times with EtOAc. The combined EtOAc layer is washed with brine, dried over MgSO4 and concentrated to a solid which is recrystallized from EtOAc/hexane to give the desired product.
