Ethanol → SGD 1882

Participants

Reaction Steps

Fresh LiBH4 (183 mg, 8.42 mmol) was added to a stirred solution of the SEM-dilactam 10 (428 mg, 0.42 mmol) in THF (5 mL) and EtOH (5 mL) at room temperature. After 10 minutes, delayed vigorous effervescence was observed requiring the reaction vessel to be placed in an ice bath. After removal of the ice bath the mixture was allowed to stir at room temperature for 1 hour. LC/MS analysis at this point revealed total consumption of starting material with very little mono-reduced product. The reaction mixture was poured onto ice (100 mL) and allowed to warm to room temperature with stirring. The aqueous mixture was extracted with DCM (3×30 mL) and the combined organic layers washed with H2O (20 mL), brine (30 mL) and concentrated in vacuo. The resulting residue was treated with DCM (5 mL), EtOH (14 mL), H2O (7 mL) and silica gel (10 g). The viscous mixture was allowed to stir at room temperature for 3 days. The mixture was filtered slowly through a sinter funnel and the silica residue washed with 90% CHCl3: 10% MeOH (˜250 mL) until UV activity faded completely from the eluent. The organic phase was washed with H2O (50 mL), brine 60 mL), dried (MgSO4) filtered and evaporated in vacuo to provide the crude material. The crude product was purified by flash chromatography (97% CHCl3: 3% MeOH) to provide the pure C2/C2′ aryl PBD dimer 11 (185 mg) 61% yield.

Provenance & Evidence