Selective Reduction by Lithium Bis- or Tris(dialkylamino)aluminum Hydrides. Ⅶ. Reaction of Lithium Tris(dihexylamino)aluminum Hydride with Selected Organic Compounds Containing Representative Functional Groups$^1$ = Selective Reduction by Lithium Bis- or Tris(dialkylamino)aluminum Hydrides. Ⅶ. Reaction of Lithium Tris(dihexylamino)aluminum Hydride with Selected Organic Compounds Containing Representative Functional Groups$^1$

다국어 초록 (Multilingual Abstract)

The approximate rates and stoichiometry of the reaction of excess lithium tris(dihexylamino)aluminum hydride(LTDHA) with selected organic compounds containing representative functional groups under the standardized conditions (tetrahydrofuran, 0$^{\circ}$C) were studied in order to define the reducing characteristics of the reagent for selective reductions. The reducing ability of LTDHA was also compared with those of the parent lithium aluminum hydride(LAH), lithium tris(diethylamino)aluminum hydride(LTDEA), and lithium tris(dibutylamino)aluminum hydride(LTDBA). In general, the reactivity toward organic functionalities is in order of $LAH{\gg}LTDEA{\geq}LTDBA>LTDHA$. LTDHA shows a unique reducing characteristics. Thus, the reagent reduces aldehydes, ketones, esters, epoxides, and tertiary amides readily. Anthraquinone is cleanly reduced to 9,10-dihydro-9,10-anthracenediol without hydrogen evolution, whereas p-benzoquinone in inert to LTDHA. In addition to that, disulfides are also readily reduced to thiols without hydrogen evolution. However, carboxylic acids, anhydrides, nitriles, and primary amides are reduced slowly. Especially, this reagent reduces aromatic nitriles to the corresponding aldehydes in good yields.