Diisobutylaluminium hydride ($(\mathrm{iBu}{)}_2\mathrm{AlH}$)

$(\mathrm{iBu}{)}_2\mathrm{AlH}$, a hydride reducing reagent. Low-temperature, controlled-stoichiometry reduction can convert an ester into an aldehyde or a lactone into a lactol; conditions must prevent further reduction.