Reduction of Organic Compounds by Alkoxyaluminohydrides

Abstract

The introduction of alkoxy groups into lithium aluminohydride, sodium aluminohydride, and aluminum hydride usually results in modification of the steric requirements and thus of the reducing properties of the parent hydrides. The reactions of these alkoxy-aluminohydrides with organic compounds are reviewed with special regard to selective reductions of functional groups in the presence of other reducible substituents, to partial reductions of esters, acid halides, amides, and nitriles to aldehydes, to stereospecific reductions of cyclic ketones and steroids and to hydrogenolytic reactions of these alkoxyhydrides in comparison with common metal hydrides. 1. Introduction 2. Preparation of Alkoxyaluminohydrides 2.1. Lithium Alkoxyaluminohydrides 2.2. Alkoxyaluminohydrides 2.3. Sodium Alkoxyaluminohydrides 3. Reactions of Alkoxyaluminohydrides 3.1. Active Hydrogen Compounds 3.2. Aldehydes and Ketones Stereospecific Reductions of Monocyclic and Bicyclic Ketones 3.3. Steroids 3.4. Carboxylic Acids and Acid Anhydrides 3.5. Esters and Lactones 3.6. Carboxylic Acid Halides 3.7. Amides, Imides, and Lactams 3.8. Nitriles 3.9. Alkyl and Aryl Halides 3.10. Epoxides 3.11. Quinones 3.12. Nitro Compounds and Their Derivatives 3.13. Other Nitrogen Compounds 3.14. Sulfur Compounds 3.15. Aromatic Hydrocarbons 3.16. Organometallic Compounds