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Conformational Analysis of Quinuclidin-3-one Derivatives

In the self-condensation reaction of quinuclidin- 3-one, two distinct isomers are produced in different ratios. To explain this difference in isomer content, full conformational analyses of all 2-(3-hydroxyquinuclidin-3-yl)quinuclidin-3-one stereoisomers were performed. Conformational spaces were calculated by using grid search methods and tensor decomposition of ab initio molecular dynamics trajectories. Grid search was performed by rigid scan and a new adaptive relaxed scan method implemented in program msa at the semiempirical level of theory using PM7 Hamiltonian. Molecular dynamics simulations were performed using on-the-fly calculations of forces in each point of the simulation and velocity Verlet algorithm for integration implemented in program qcc. Principal component analysis was used as a dimensionality reduction tool and performed using a NIPALS algorithm implemented in program moonee. Complete conformational spaces for investigated compounds in the ground state have been determined and results obtained from each individual method have been compared. Use of principal component analysis on generated molecular dynamics trajectories provided the complete set of conformers for every investigated system contrary to the grid search methods, which excluded some of them. Full conformational spaces of enantiomeric pairs were determined with exact match between enantiomeric conformers confirming the validity of used methods and these results are used to explain the differences in self- condensation reaction products.

conformational analysis, tensor decomposition, quinuclidin-3-one derivatives

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