1: 91 percent / Bu3P / benzene / 60 °C 2: 3-n-butyl-1,2-benzisothiazole-1,1-dioxide oxide / 48 h 3: NaBH4, AcOH 4: 87 percent / H2 / Pd/C / methanol / 0.25 h / 760 Torr View Scheme