Reduction by complex metal hydrides

Addition of hydride to the carbonyl carbon to form an alcohol, or the reverse, changes the oxidation state and so is usually classified separately from other carbonyl reactions. Some of these processes are nevertheless fundamentally similar to the ones we have been considering. Reductions by complex metal hydrides, such as lithium aluminum hydride or sodium borohydride, are additions ofH - (Equation 8.27) the metal hydride ion is simply a convenient source of this extremely basic species. The carbonyl oxygen takes the place of the hydride in coordination with the boron (or aluminum in the case of an alumino-... 

As with tetrahydro-1,3-oxazines the tetrahydro-1,4-oxazine ring system is stable to reduction by complex metal hydrides, and, for example, LAH can be used to reduce the lactam carbonyl function of mor-... 

There are a few examples of hydroxyl group participation in reductions by complex metal hydrides. Franzus and Snyder " report that reduction of norbornadiene-7-ol (258) or its acetate with lithium aluminum hydride results only in reductive formation of (2nti-7-norbornenol. Use of LiAlD4 and H2O work-up yields a single deuterium incorporation in an exo position. D2O work-up leads to the incorporation of a second xo-deuterium. The reaction was thus formulated to occur as shown in Scheme 12. Borden has published studies that indicate that the step (259)-(260) occurs with intramolecular deuteride attack. 

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