124 125 The [12]annulene 124 has been prepared.314 In solution, 124 undergoes rapid con- formational mobility (as do many other annulenes),315 and above 150C in this par- tiuclar case, all protons are magnetically equivalent. However, at 170C the mobility is greatly slowed and the three inner protons are found at
8 d while the nine outer protons are at
6 d. Interaction of the ‘‘internal’’ hydrogens in annulene 124 leads to nonplanarity. Above 50C, 124 is unstable and rearranges to 125. Several bridged