3-Chloro-2-butanone reacts with 1,4-dianion of acetophenone N-ethoxycarbonylhydrazone to yield pyrazoline derivatives.3-Chloro-2-butanone was used in production of chiral alcohols from acetophenone derivatives, β-ketoesters and N-Boc-3-pyrrolidinone by recombinant E. coli cells. It was used in the synthesis of carbene precursor, 3-aryl-4,5-dimethylthiazolium chloride. 3-Chloro-2-butanone reacts with 1,4-dianion of acetophenone N-ethoxycarbonylhydrazone to yield pyrazoline derivatives. 3-Chloro-2-butanone was used in production of chiral alcohols from acetophenone derivatives, β-ketoesters and N-Boc-3-pyrrolidinone by recombinant E. coli cells. It was used in the synthesis of carbene precursor, 3-aryl-4,5-dimethylthiazolium chloride.