An One-Pot Synthesis of Semibullvalenes and Its Mechanism

Theory, Experiment and Unusual Features of Potential Energy Surfaces of Pericyclic and Pseudopericyclic Reactions with Sequential Transition Structures

“…(4) [15]. The PES was calculated at several levels of theory by Kraka et al and is illustrated in Fig.…”

Three-Membered-Ring-Based Molecular Architectures

“…80 Such [4 + 2] cycloadditions of 3,3′-bicyclopropenyls were also performed with triazines, 81 R-pyrons, 81 1,3,4-oxadiazoles, 82 and unsymmetrically substituted tetrazines. 83 Interesting rearrangements of 3,3′-bicyclopropenyl as a valence isomer of benzene have also triggered a number of theoretical investigations. Castenmiller and Buck were the first to report on results of semiempirical MINDO/3 and ab initio calculations at the STO-3G level of theory for various structures on the C 6 H 5 + potential energy surface.…”

Recent Advances in Cyclopropene Chemistry

“…Sauer further showed that the reaction of biscyclopropenyl 142 with tetrazines can serve as a straightforward approach to semibulvalenes 145 (Scheme 86). 150 This onepot transformation proceeds via initial intermolecular [4+2] cycloaddition to give anti-143, which epimerizes into syn-143. The latter then undergoes a second intramolecular [4+2] cycloaddition to afford pentacyclic framework 144, which spontaneously rearranges to semibulvalene 145 upon loss of nitrogen.…”

“…The latter then undergoes a second intramolecular [4+2] cycloaddition to afford pentacyclic framework 144, which spontaneously rearranges to semibulvalene 145 upon loss of nitrogen. 150 Despite the clear aromatic character of 1,3,5-triphosphabenzene 146, this compound exhibits surprisingly high reactivity in Diels-Alder reactions. 151 Thus, [4+2] cycloaddition of 146 with unsubstituted cyclopropene proceeds at -78°C; however, the reaction cannot be stopped at the formation of monoadduct 147.…”