Computational Studies on the Electrocyclizations of 1-Amino-1,3,5-hexatrienes
journal contributionposted on 12.11.2004, 00:00 by Vildan Adar Guner, K. N. Houk, Ian W. Davies
Electrocyclizations of 1,3,5-hexatrienes containing up to four electron-donating and/or electron withdrawing substituents have been studied computationally using the hybrid density functional, B3LYP. Electron donating substituents at positions C-1 and C-5 decrease activation barriers by 0.3 to 2.3 kcal/mol. Introducing of an electron-withdrawing group, CO2Me, at C-4 further decreases the activation energy by 7 kcal/mol. Electron-withdrawing groups (NO2, SO2Ph and CN+Me2) at C-2 have a profound effect of 17−25 kcal/mol on the activation energy.