NaBH₄ Reduction: Aldehydes & Ketones → Alcohols (Mechanism + Selectivity)

Master NaBH4 reductions: hydride transfer mechanism, chemoselectivity vs LiAlH4, stereochemical outcomes, and practice problems.

• Reaction: C=O → alcohol
• What it does: Reduces aldehydes/ketones (usually not esters/amides)
• Typical reagents: NaBH4 in MeOH/EtOH; then workup
• Key intermediate: Alkoxide + borate
• Driving force: Hydride transfer; protonation gives alcohol
• Exam type: Reagent selection
• Exam type: Chemoselectivity
• Exam type: Predict product