1: NaBH4 / 10percent Pd/C / methanol 2: 60 percent / sodium perborate, trifluoroacetic acid / 24 h / Heating View Scheme

sodium tetrahydroborate; palladium on activated charcoal in methanol

in dichloromethane addn. of S-comp. to small portions of (CF3CO)2O and 90 to 99percent H2O2, after an hour addn. of (CF3CO)2O and 90percent H2O2, mild reflux 10 h;