Centrohexaindanes Bearing Methyl Groups in Their Molecular Propellane Cavities

摘要

The syntheses of two new centrohexaindane derivatives bearing methyl groups in their molecular propellane-type cavities are described.These new topologically non-planar hydrocarbons,1,8-dimethylcentrohexaindane 6 and 1,4,8,28-tetramethylcentrohexa-indane 7 were obtained from suitable 1,3-indanediones following the shortest aufbau strategy,the propellane route,representing a six-step access to these unusually highly condensed polycyclic hydrocarbons.X-ray single crystal structure analysis of 6 revealed that the presence of the two methyl groups in the cavities of the centrohexaindane framework does not give rise to significant distortion of the T_d-symmetrical molecular skeleton;however,their efficient hiding within two of the four equivalent cavities allows for strong intermolecular disorder in the crystal.