text:  The earliest efforts to improve the selectivity of the <unk> <unk> took advantage of the β @-@ silicon effect in order to direct the <unk> of the elimination step . This chemistry was developed most extensively by Professor Scott Denmark of the University of Illinois , <unk> @-@ <unk> in the mid @-@ 1980s and utilizes stoichiometric amounts of iron <unk> to promote the reaction . With <unk> products , the <unk> <unk> was selected for to varying degrees . 
  