text:  An <unk> is an organic molecule that features a three @-@ membered <unk> containing oxygen , nitrogen , and carbon . In their largest application , <unk> are intermediates in the industrial production of hydrazine . <unk> derivatives are also used as specialized reagents in organic chemistry for a variety of oxidations , including alpha hydroxylation of <unk> , epoxidation and <unk> of olefins , and other heteroatom transfer reactions . <unk> also serve as precursors to amides and participate in [ 3 + 2 ] cycloadditions with various <unk> to form substituted five @-@ membered <unk> . Chiral <unk> derivatives effect asymmetric oxygen transfer to <unk> <unk> as well as other substrates . Some <unk> also have the property of a high barrier to inversion of the nitrogen , allowing for the possibility of chirality at the nitrogen center . 
  