After being held at reflux for 2 h, the volume was reduced to approximately half by distillation, and the residues poured into ice water. The solids were removed quickly by filtration, washed well with H2O, and air-dried. The unpurified isolate can be used directly in the next step. A round-bottom flask was equipped with a mechanical stirrer, a reflux condenser, and a means of cooling with an external water bath. With good stirring, there was gentle heating applied until an exothermic reaction set in, and this was maintained at a controlled pace with external cooling.
Catalytic hydrogenation is an alternate process for reduction.
The organic phase was dried over anhydrous MgSO4, then the solvent was removed under vacuum. The greenish-black residue was triturated with 4x100 mL portions of boiling cyclohexane. The addition took 20 min. The solvents were removed under vacuum, and the residue treated with 100 mL each of H2O and CHCl3. The organic phase was separated, the aqueous phase extracted with additional CHCl3, the pooled extracts dried over anhydrous MgSO4, filtered, and the filtrate evaporated under vacuum.