 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 , Urbana @-@ Champaign in the mid @-@ 1980s and utilizes stoichiometric amounts of iron trichloride to promote the reaction . With bicyclic products , the cis isomer was selected for to varying degrees . 
