▁some ▁of ▁the ▁earlier ▁prepar ations . ▁ ▁In ▁the ▁original ▁synth esis ▁of ▁this ▁subst ance ▁by ▁L aden burg ▁in ▁ 1 8 8 6 , ▁N - m eth yl py rid ine , ▁as ▁its ▁i od ide ▁salt , ▁was ▁is omer ised ▁at ▁ 2 5 0   ° C ▁to ▁obtain ▁ 2 - m eth yl py rid ine ▁( α - p icol ine ). ▁Re action ▁of ▁this , ▁as ▁shown ▁in ▁the ▁scheme ▁below , ▁with ▁the ▁cy clic ▁tr imer ▁of ▁ac etal de hy de , ▁par al de hy de , ▁in ▁the ▁presence ▁of ▁a ▁base ▁gave ▁ 2 - pro pen yl py rid ine ▁via ▁a ▁Kno even ag el ▁cond ens ation . ▁This ▁intermediate ▁was ▁reduced ▁with ▁met all ic ▁sod ium ▁in ▁eth an ol ▁or ▁by ▁hydro gen ▁gas ▁( as ▁shown ) ▁to ▁provide ▁rac em ic ▁( ± ) ▁con i ine . ▁En anti op ure ▁con i ine ▁was ▁then ▁obtained ▁by ▁a ▁ch iral ▁resolution , ▁specifically , ▁fraction al ▁cry st all isation ▁of ▁the ▁di aster e omer ic ▁(+ )- t art ar ic ▁acid ▁salt . ▁ ▁The ▁initial ▁reaction , ▁however , ▁gives ▁a ▁poor ▁yield ▁and ▁was ▁improved ▁by ▁interaction ▁of ▁the ▁two ▁re ag ents ▁at ▁ 1 5 0   ° C ▁in ▁se aled ▁tub es ▁to ▁give ▁m eth yl - 2 - p icol yl alk