hydrogen in tetrahydrofuran addn. of butoxide to soln. of Cu-compd. (stirring, Ar atmosphere), addn. of H2 (80 psi, stirring, 16 h); solvent removal, extn. (toluene), filtration (Celite), crystn. (layeredwith acetonitrile), filtration (Ar atmosphere), drying (vac.);