CIDNP Study and Ab-Initio Calculations of Rigid Vinylcyclopropane Systems: Evidence For Delocalized “Ring-Closed” Radical Cations

Radical cations of disubstituted cyclopropanes: stereoelectronic effects on hyperfine coupling

“…For bicyclic derivatives, in which the functionalities are locked in either the syn or the anti configuration, electron transfer‐induced CIDNP effects suggest a range of structure types with subtle differences. Either the internal cyclopropane bond, or a lateral one, or possibly two bonds are involved in delocalizing spin and charge . These results support stereochemical prerequisites for the delocalization of an unpaired spin into the cyclopropane and vinyl functionalities, respectively, and the electronic interactions between these moieties …”

“…Non‐symmetrically disubstituted cyclopropane radical cations containing a vinyl group have been probed by experiment and calculation . For bicyclic derivatives, in which the functionalities are locked in either the syn or the anti configuration, electron transfer‐induced CIDNP effects suggest a range of structure types with subtle differences.…”

Substituent Effects in the Vinylcyclopropane Radical Cation Rearrangement: A Computational Road to a New Synthetic Tool

“…Since the barrier for rotation around the C3ϪC4 bond is relatively high at ca. 19 kcal/ mol, [10] the syn/anti ratio in the radical cation will be determined by this ratio in the corresponding neutral vinylcyclopropane. The predominant conformation of substituted vinylcyclopropane radical cations can be estimated, therefore, by using much simpler methods, for example force-field calculations.…”

“…[9] A more recent study, of the electronic structures of syn-1 ·؉ and anti-1 ·؉ and their relationships to neutral 1 at the MP2/6-31G* level, was published by Herbertz et al [10] The reactivity, however, of the vinylcyclopropane radical cation was not studied compu-tationally until recently, when our group investigated the structure and reactivity of 1 ·؉ at the B3LYP/6-31G* and QCISD(T)/6-31G*//QCISD/6-31G* levels of theory. [11] More recently, our study was duplicated by Hofmann and Schaefer, employing a different high-level ab initio method [CCSD(T)] for the final energy calculations.…”

Triphenylpyrylium Tetrafluoroborate-Sensitized Photochemistry of the Terpenes Sabinene, α-Phellandrene, and α- and γ-Terpinene

“…vinylcyclopropane systems [sabinene (1), [27] α-(2) and βthujene, [28] 2-carene], [29] and vinylcyclobutane species (αand β-pinene). [25,26,30] In a few cases, the intramolecular capture of terpene radical cations by tethered nucleophiles (OH functions) was probed.…”