Towards the synthesis of dodecahedrane II. The crystal and molecular structure of tetrahydro-C₁₆-hexaquinacene-1,9-dione*

Structure of pentacyclo[7.4.2.02,6.06,15.011,14]pentadec-4-ene-7,13-dione, a novel pentacyclic C15 quinane system

“…The torsion angles within the rings (Fig. 2) show that all the five-membered rings are in envelope conformations (C s symmetry) with ring A slightly molecule with six fused five-membered rings (Engel, Sobczak & Paquette, 1980), three of the rings are planar and the other three are distorted half-chairs, and in the 1,16-dimethyl derivative of dodecahedrane (Paquette, Balogh, Usha, Kountz & Christoph, 1981), because of the methyl substitution, only the flanking five-membered rings show a slight non-planarity. It appears from these observations that the cyclopentane ring is constrained to be planar in higher polyquinanes leading to dodecahedrane.…”