Hydroboration is the anti-Markovnikov hydration of an alkyne. A hindered borane (dicyclohexylborane or diisoamylborane) is used as a reagent, obtaining an enol that tautomerizes to aldehyde or ketone. Terminal alkynes give rise to aldehydes, internal ones to ketones.
![hydroboration alkynes01](/images/stories/organica-i/alkynes/hidroboracion/hidroboracion-alquinos01.png)
[1] Dicyclohexylborane (Cy2BH)
[2] Diisoamylborane
![hydroboration alkynes01 2](/images/stories/organica-i/alkynes/hidroboracion/hidroboracion-alquinos01-2.png)
The mechanism of the reaction goes through the following steps:
Stage 1. Addition of the borane to the triple bond. Boron is attached to the least substituted carbon of the alkyne.
![hydroboration of alkynes hidroboración de alquinos](/images/stories/organica-i/alkynes/hidroboracion/hidroboracion-alquinos02.png)
Stage 2. Oxidation of borane to alcohol
![hydroboration of alkynes hidroboración de alquinos](/images/stories/organica-i/alkynes/hidroboracion/hidroboracion-alquinos03.png)
Stage 3. Keto-enol tautomerism
![hydroboration of alkynes hidroboración de alquinos](/images/stories/organica-i/alkynes/hidroboracion/hidroboracion-alquinos04.png)