Electroreduction of Organic Compounds, 37 [1]. Electroreduction of 1,4-Dichlorobicyclo[2.2.2]octane-2-carboxamides

Abstract

Several 1,4-dichlorobicyclo[2.2.2]octanecarboxamides were prepared, which were expected to be suitable precursors for the electrochemical synthesis of [2.2.2]propellanes. Their potentiostatic electroreduction at extremely negative potentials in THF, however, did not lead to the expected [2.2.2]propellanes. Instead, protio-dechlorination to form the corresponding bicyclo[2.2.2]octanecarboxamides occurred, even under rigorous exclusion of moisture and oxygen. Ring-opened olefins were produced as by-products. Polytetrahydrofuran was formed when the supporting electrolyte tetrabutylammonium hexafluorophosphate was electrolyzed at −3.5 V in the absence of an organic chloro compound as depolarizer. The experimental results are interpreted in terms of semi-empirical MO calculations.

The Influence of Multiple Fluorination on the Ring Opening of [2.2.2]Propellane

“…The energy barrier with respect to 12a increases by 0.4 and 0.3 kcal mol -1 at CASSCF and CASPT2 levels of theory, respectively. We note in passing that this is in contrast with MNDO results by J. Voss et al [14] who found an increase of the barrier by 8 kcal mol -1 as compared to 2a. [14] …”

“…We note in passing that this is in contrast with MNDO results by J. Voss et al [14] who found an increase of the barrier by 8 kcal mol -1 as compared to 2a. [14] …”

“…It is interesting to note that recent attempt to prepare 2a, as well as similar carboxyamido-[2.2.2]propellane derivatives 3a and 4a, by electroreduction of 1,4-dichlorobicyclo[2.2.2]octane-2-carboxamides failed. [14] Further stabilisation of the [ [15,16] The first among them (5a) rearranges to a mixture of the corresponding 1,4-dimethylenecyclohexanes with a half-time of 40 hours at 21 °C, while 6a showed no signs of decomposition even after heating at 100 °C for more than 10 hours.…”