To be complete, I wasn’t reducing an ester, it was a thioimide. It was an (OH-protected) aldol adduct utilizing a thiazolidinethione as a chiral auxiliary. We developed the conditions for the aldol addition in our laboratory. Suffice it to say we did the diastereoselective aldol addition a lot . Partial reduction of the thioimide to the aldehyde was a common next transformation, so we always had a fresh bottle of DIBAL in the fridge. I reduced 5 different thioimides this way who knows how many times as I ran through the synthetic scheme who knows how many times.
Benzoic acid occurs naturally as do its esters in many plant and animal species. Appreciable amounts have been found in most berries (around %). Ripe fruits of several Vaccinium species (., cranberry , V. vitis macrocarpon ; bilberry , V. myrtillus ) contain as much as –% free benzoic acid. Benzoic acid is also formed in apples after infection with the fungus Nectria galligena . Among animals, benzoic acid has been identified primarily in omnivorous or phytophageous species, ., in viscera and muscles of the rock ptarmigan ( Lagopus muta ) as well as in gland secretions of male muskoxen ( Ovibos moschatus ) or Asian bull elephants ( Elephas maximus ).