text:  In the late 1970s and early 1980s Franklin A. Davis synthesized the first N @-@ <unk> , which act exclusively as oxygen transfer reagents , and are the most predominantly used class of <unk> today . While originally synthesized with <unk> and the phase transfer catalyst <unk> chloride , an improved synthesis using <unk> as the <unk> is now most prevalent . 
  