Two mechanisms of migration of benzhydryl and benzyl groups in the pentamethoxycarbonylcyclopentadiene ring

期刊论文
发表日期：

2025年9月1日

查看全文

G. A. Dushenko,
O. I. Mikhailova,
I. E. Mikhailov

摘要

The DFT CAM-B3LYP/6-311++G(d,p) method showed that two migration mechanisms are possible for the 4-methoxybenzyl group in the pentamethoxycarbonylcyclopentadiene ring, namely, 1,5-sigmatropic shifts with an energy barrier ΔE^≠_ZPE = 32.5 kcal mol⁻¹ in the gas phase and a dissociative pathway through the formation of a tight ion pair with a lower activation barrier ΔE^≠_ZPE = 24.2 kcal mol⁻¹ in methanol (PCM). In contrast, the 4-nitrobenzyl group migrates in this system only via 1,5-sigmatropic shifts both in the gas phase and in methanol with higher activation barriers ΔE^≠_ZPE = 33.6 and 33.3 kcal mol⁻¹, respectively, whereas migrations of the benzhydryl group in the pentamethoxycarbonylcyclopentadiene ring occur via the dissociation—recombination mechanism both in the gas phase and in methanol with fairly low activation barriers ΔE^≠_ZPE = 24.0 and 21.5 kcal mol⁻¹, respectively.