The octaethyl triptycenes 7 and 8 were synthesized by Diels−Alder reaction of the octaethylanthracene 4with the corresponding benzynes. Low-temperature NMRspectra of 7 and 8 are consistent with the presence of thefully alternated conformation “a” of C2 symmetry. However,in the determined crystal structures, the compounds adopta higher energy conformation with a pair of vicinal ethylsoriented in the same direction.