The elimination of 5−bromononane on treatment with potassium ethoxide is stereoselective. Select the correct Newman projections of 5−bromononane showing the conformations that lead to cis−4−nonene and trans−4−nonene, respectively. Identify the proton that is lost in each case by selecting the Newman projections that have this hydrogen colored blue. Suggest a mechanistic explanation for the observed stereoselectivity. Leads to cis−4−nonene:
