Lithium triisobutylhydroborate is a highly selective hydride reducing agent, structurally related to lithium tri-sec-butylborohydride (L-Selectride). It is a colorless to light yellow solution, typically supplied in tetrahydrofuran (THF) or diethyl ether. This reagent is characterized by its bulky trialkylborohydride structure, which provides exceptional steric hindrance for chemoselective reductions. Its primary application is in organic synthesis as a powerful and stereoselective reducing agent. It is widely used for the reduction of ketones, aldehydes, and esters to their corresponding alcohols, often with high diastereoselectivity. The bulky nature of the triisobutylborane moiety allows for the preferential reduction of less hindered carbonyl groups, making it a valuable tool for complex molecule synthesis, including natural products and pharmaceuticals. It is also employed in the reduction of epoxides and alkyl halides. This reagent is highly air- and moisture-sensitive, requiring handling under an inert atmosphere. It is a strong base and can deprotonate acidic protons. Due to its specialized nature and high cost, it is primarily used in research and development laboratories for fine chemical synthesis rather than in large-scale industrial processes.