Al-NiCl₂·6H₂O: A Mild and Efficient System for Selective Reduction of Functional Groups in Organic Synthesis

Introduction

The most common broad-spectrum reducing agents are metal hydrides like LiAlH₄, NaBH₄, DIBAL-H, and 9-BBN. Apart from this, some hydrogenation catalysts have been investigated in order to find conditions under which a given group will be reduced chemoselectively. [1] Metal-metal-salt binary systems such as Al-NiCl₂·6H₂O·THF, [2] Al-SbCl₃ or Zn-SbCl₃, [3] Fe-NiCl₂·6H₂O·THF, [4] or Sm-NiCl₂·6H₂O·THF [5] have long been used as reducing agents for many functional groups.

Reagents based on aluminum find wide application in ­organic synthesis. [6] The Al-NiCl₂·6H₂O system is a highlight in current organic chemistry due to its selectivity, mild reaction conditions, easy handling, low cost, and convenient isolation process.

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