Pulse Radiolysis and 77 K Matrix γ Irradiation of Dimethyl Truxinates and trans-Methyl Cinnamate in 2-Methyltetrahydrofuran

Article abstract of DOI:10.1021/j100207a025

One-electron reduction of dimethyl μ-truxinate (μ-DMT), dimethyl β-truxinate (β-DMT), and dimethyl α-truxillate (α-DMT) has been investigated by pulse radiolysis and 77 K matrix γ irradiation of the 2-methyltetrahydrofuran solutions.Cycloreversion of the radical anions formed by an electron attachment to these cyclobutanes was observed in all cases, even at 77 K.The orientation of the cycloreversion was dependent on the stereochemistry of the cyclobutanes, and the selectivity was reasonably explained by a so-called cis effect; the best possible release of steric hindrance decides the primary step of the reaction.In 77 K matrix γ irradiation of α-DMT, an intense IR absorption was found after the photobleaching of trapped electrons with light >690 nm.In other DMTs, the IR absorption band was not observed while the cycloreversion of DMT by mobile electrons occurred.Thus, the IR band in the case of α-DMT was assigned to an associated dimer anion due to the interaction between the radical anion and the neutral molecule pair of trans-methyl cinnamate originally formed by the cycloreversion of α-DMT.The dimer anion was presumed to be oriented in a head-to-tail structure in a solvent cage on the basis of the original configuration of α-DMT.