The Borane di(tert-butyl)phosphine complex is primarily utilized in organic synthesis as a reducing agent and catalyst. It is particularly effective in the reduction of various functional groups, including carbonyl compounds, to their corresponding alcohols. This complex is also employed in the synthesis of organophosphorus compounds, where it facilitates the formation of phosphine derivatives. Additionally, it plays a role in the preparation of fine chemicals and pharmaceuticals, aiding in the creation of complex molecular structures. Its stability and reactivity make it a valuable tool in research and industrial applications, where precise control over chemical reactions is essential.