Reagents and conditions: a) (1) AgOTf, p-TolSCl, MS 4Å, −78°C, then 19, TTBP, −78°C–0°C; (2) Tf2O, THF, H2O; b) AgOTf, p-TolSCl, MS 4Å, −78°C, then 5, TTBP, −78°C–0°C; c) (1) AcOH, NH2NH2, DCM/MeOH; (2) 22, AgOTf, p-TolSCl, MS 4Å, TTBP, −78°C–0°C; d) AgOTf, p-TolSCl, MS 4Å, −78°C, then 23, TTBP, −78°C–0°C; e) AgOTf, p-TolSCl, MS 4Å, −78°C, then 5, TTBP, −78°C–0°C; f) AcOH, NH2NH2, DCM/MeOH.