Intramolecular [3 + 4] cycloaddition in substituted dispiro[2,3,x]alkanes. A new pathway to polycyclic olefins containing cycloheptene
作者:Shalom Sarel、Avraham Felzenstein、Joseph Yovell
DOI:10.1039/c39740000753
日期:——
A novel cycloreaction involving intramolecular addition of cyclopropane to a tetrasubstituted cyclobutane contained in a dispiro-system to form a seven-membered ring is described.
Two alternativemodes of addition to vinyl-cyclopropane systems are here described for each of two dienophiles: tetracyanoethylene is shown to react either via[2 + 2] or by [2 + 4] cycloadditions; and dimethyl acetylenedicarboxylate reacts either by the ‘ene’ route or by way of insertion to the double bond.