ADDITION-COMPOUNDS OF ALKALI-METAL HYDRIDES .17. UNUSUAL REACTION OF TRIALKYLBORANES WITH LITHIUM TRI-TERT-BUTOXYALUMINOHYDRIDE IN TETRAHYDROFURAN

Addition of equimolar or catalytic quantities of trialkylboranes to a tetrahydrofuran solution of lithium tri-t-butoxyaluminohydride results in rapid loss of active hydride with the concurrent formation of 1-butanol (from the reductive cleavage of tetrahydrofuran). The rate of reductive cleavage decreases with increasing steric requirements of the trialkylborane. In contrast to the tetrahydrofuran, tetrahydropyran is cleaved sluggishly. Consequently, this solvent can be utilized to follow the course of the reaction of lithium tri-t-butoxyaluminohydride with representative trialkylboranes by 11B NMR. Chemical and spectral evidence suggest the intermediacy of lithium trialkylborohydrides and aluminum-t-butoxide in these reactions. © 1979.