Atropisomers of 2, 3-dichloro-9-(1-hydroxy-1-methylethyl) triptycene were obtained as stable compounds at room temperature. The barrier to rotation (±sc→ ap) was 34.0 kcal/mol at 153° C. Other 9-(1-hydroxy-1-methylethyl) triptycenes carrying a substituent in the 1-position of the skeleton gave±sc isomers only. Attempted isomerization of the±sc forms failed because the free energy difference between the±sc and ap forms is great due to the steric ...