Deciphering the Molecular Mechanism of Intramolecular Reactions from the Perspective of Bonding Evolution Theory

The molecular mechanisms of three intramolecular rearrangements (I, the rearrangement allyloxycycloheptatriene to yield tricyclic ketones; II, cycloaddition a nitrone-alkene render two isoxazolidines; and III, decomposition N-carbamoyl-L-proline in tetrahydro-1H-pyrrolo[1,2-c]imidazole-1,3(2H)-dione plus water, or tetrahydro-1H,3H-pyrrolo[1,2-c]oxazole-1,3-dione ammonia) have been studied by means bonding evolution theory (BET). thermal I is composed sigmatropic coupled an Diels–Alder reaction. reaction comprises four steps: (1) rupture O-C single chemical bond, (2) transformation C-O double (3) creation pseudo-radical centers on carbon atoms with C-C bond evolving other migration, (4) formation new bond. For reaction, process can be described as initial up monosynaptic V(C) basins successive steps, loss character bonds, followed consecutive sensed between first second bonds. forming depopulation N-C bonds V(N) basins, bond-forming processes via V(O,C) V(C,C) disynaptic basins. Finally, for mechanism water elimination takes place events which summarized follows: C-N, transfer its population V(O), restoration N nitrogen lone pair H-N cleavage, O-H illustrating molecule release. case deamination, correspond breaking H-O respectively, while last deal NH3 molecule.