Hydroboration–Oxidation of Alkynes: Anti‑Markovnikov Hydration → Aldehydes/Ketones

Learn hydroboration–oxidation of alkynes. Syn addition of borane, anti‑Markovnikov regiochemistry, oxidation to enol, and tautomerization.

• Reaction: RC≡CH → aldehyde (terminal) or ketone (internal)
• What it does: Hydrates alkynes anti‑Markovnikov (vs HgSO4 hydration)
• Typical reagents: 1) bulky borane (e.g., 9-BBN, disiamylborane) 2) H2O2, NaOH
• Key intermediate: Vinyl borane; enol
• Driving force: Oxidation replaces B with OH; tautomerization gives carbonyl
• Exam type: Regiochemistry
• Exam type: Reagent selection
• Exam type: Predict product