A new method for the synthesis of diamantane by hydroisomerization of binor-S on treatment with sulfuric acid

A new method was developed for the direct synthesis of the second representative of the homologous series of diamondlike hydrocarbons, diamantane, in 65% yield by hydroisomerization of the norbornadiene dimer, endo-endoheptacyclo[8.4.0.0(2)(,)(12).0(3,8).0(4,6).0(5,9).0(11,13)]tetradecane (binor-S) on treatment with concentrated sulfuric acid (98%). In the presence of H2SO4 of lower concentration (75-80%), the reaction stops after the hydrogenation step giving endo-endo-pentacyclo[7.3.1.1(2,5).1(8,10)0(3,7)] tetradecane in 68% yield with excellent selectivity (100%).