Restricted Rotation Involving the Tetrahedral Carbon. XXXI. Barriers to Rotation in 2,3-Dichloro-9-(1-cyano or 1-methoxycarbonyl-1-methylethy)triptycenes

Abstract

The title compounds were prepared to see the effects of substituents in 1-position on the barriers to rotation about the C9–Csubst bond. The barrier was found to be higher for the cyano compound than those for the corresponding compounds carrying a substituent in 1-position, whereas the methoxycarbonyl compound gave almost the same barrier irrespective of the substituent.

Structures of ap-8-bromo-1,4-dimethyl-9-(2-methylbenzyl)triptycene and sc*(9S*)-8-bromo-1,4-dimethyl-9-(2-methylbenzyl)triptycene

“…Several examples of atropisomerism have been found in 9-substituted triptycene derivatives (Iwamura, 1973;Yamamoto & Old, 1975;Otsuka, Yamamoto, Mitsuhashi & Old, 1979;Otsuka, Mitsuhashi & Old, 1980;Yamamoto, Suzuki & Old, 1981;Yonemoto, Kaldzald, Yamamoto, Nakamura & Old, 1985;Tanaka, Yonemoto, Nakai, Yamamoto & Old, 1988;Old, Tanuma, Tanaka & Yamamoto, 1988). Recently 8-chloro-and 8-bromo-l,4-dimethyl-9-(2-methylbenzyl)triptycene were synthesized (Yamamoto, 1990(Yamamoto, , 1991 2-methylphenyl group lies between twoperi substituents.…”