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 ). 
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.