What is "disiamylborane"

n. (context organic compound English) The organic borane ''bis(1,2-dimethylpropyl)borane'' that is used to synthesize aldehydes from alkynes

Disiamylborane (bis(1,2-dimethylpropyl)borane) is an organoborane used in organic synthesis. It is used to add water to a terminal alkyne, forming an aldehyde via anti-Markovnikov addition. Disiamylborane is relatively selective for terminal alkynes. It also is used for the selective functionalization of terminal alkenes.