M. Ōki, T. Tanuma, Yasuhiro Tanaka
Dec 1, 1988
Citations
0
Influential Citations
12
Citations
Journal
Bulletin of the Chemical Society of Japan
Abstract
Rotational isomers of 3-methyl-3-(1,2,3,4-tetrahalo-9-triptycyl)butanoic acid, where the halo is either fluoro or chloro have been prepared. Cyclization of their acid chlorides afforded ap- and sc-ketones from ap- and sc-isomers, respectively. The barriers to isomerization were 29.9 and 26.8 kcal mol−1 at 363 K, for the fluoro and the chloro ketones, respectively, for the ap→±sc process. The equilibrium constants (sc/ap) at 363 K were 2.34 and 18.5 for the fluoro and the chloro compounds respectively. The barriers to isomerization and the relative stabilities of the isomeric ketones were discussed based on the MMP2(NONPLANAR) calculation results and the steric congestion in the ground state.