2.1.4 Diisobutylaluminum Hydride (DIBAL-H)

The diisobutylaluminum hydride (DIBAL-H) is a commercially available selective reducing agent. It can selectively reduce esters and nitriles to the corresponding aldehydes. The reaction is carried out in inert and moisture free atmosphere.

P. Galatsis, Encyclopedia of Reagents for Organic Synthesis, John Wiley and Sons, Inc., L. A. Paquette, Ed., New York, 1995, 3, 1908.

2.1.4.1 Reduction of Esters to Aldehydes

The esters are selectively reduced to the corresponding aldehydes at low temperature. The DIBAL-H transfer one hydride to the ester group and forms a tetrahedral intermediate which is stable at low temperature. The hydrolytic work up of the intermediate gives the desired aldehydes (Scheme 13). The presence of alkoxy or amino group to the close proximity can stabilize the tetrahedral intermediate and hence give better result. 

Scheme 13