Abstract
| - The [4 + 2] cycloaddition of trans,trans-2,4-hexadiene with C60 proceeds via a concerted mechanismwith retention of stereochemistry in the cycloadduct 1a. However, when cis,trans-2,4-hexadienereacts with C60, isomerization of the cis,trans to the thermodynamically more stable trans,transisomer occurs. Subsequently, the cis,trans diene isomerized to the trans,trans isomer and cycloaddsto C60, to form adduct 1a. When the reaction is carried out at higher temperatures, the formationof cycloadduct 1b is also obtained. This result is consistent with a concerted cycloaddition ofcis,trans-2,4-hexadiene with C60, which is more reactive at elevated temperatures and leads to theformation of the Diels−Alder adduct 1b.
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