text: Thioesters are prominent active esters, as illustrated by the esters of coenzyme A.
  In synthetic chemistry, active esters include derivatives of nitrophenols and pentafluorophenol. Active esters are often used in peptide synthesis, e.g., N-hydroxysuccinimide, hydroxybenzotriazole. Active esters of acrylic acid are precursors to polymers with reactive side chains.
  The concept of active esters extends to esters of phosphoric and sulfuric acids. One such case is dimethylsulfate, a strong methylating agent.