CO[C:3]1[CH:4]=[CH:5][C:6]2[S:10][C:9]([CH3:12])([CH3:11])[NH:8][C:7]=2[CH:13]=1.[BH4-].[Na+].[C:16](O)(=[O:18])C>C(COC)OC.C(O)(C)C>[CH:9]([NH:8][C:7]1[CH:13]=[CH:3][C:4]([O:18][CH3:16])=[CH:5][C:6]=1[SH:10])([CH3:11])[CH3:12]To 5-methoxy-2,2-dimethylbenzothiazolidine (14.6 gm; 75 mmoles) in 50 ml dimethoxyethane and 5 ml isopropanol was added sodium borohydride (4.0 gm; 0.1 mole). The reaction mixture was stirred at room temperature for 1 hour. The mixture was then poured over 5 N acetic acid, extracted with methylene chloride, washed with brine, dried (Na2SO4) and concentrated in vacuo. The residue was recrystallized from hexane to yield the title compound, m.p. 68°-69° C. in nearly quantitative yield.
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