title: The conformational behavior, geometry and energy parameters of Menshutkin-like reaction of O-isopropylidene-protected glycofuranoid mesylates in view of DFT calculations.
abstract: The formation of pyridinium salts in the transformation of three O-isopropylidene-protected mesylates of furanoid sugar derivatives under pyridine action is considered at the B3LYP/6-31+G** computation level. All the structures were optimized in the gas phase, in chloroform and water. Activation barrier heights in the gas phase were also estimated at the B3LYP/6-311++G**, MPW1K/6-31+G** and MPW1K/6-311++G** levels. The conducted calculations, both in the gas phase (regardless of the computation level) and in solvents, revealed the barrier height increasing order as follows: 1>2>3 for the three reactions studied. The conformational behavior of the five-membered ring is discussed in the gas phase and in solvents. The fused dioxolane ring makes the furanoid ring less likely to undergo conformational changes. In the case of reaction 3, the furanoid ring shape does not change either in the gas phase or in solvents. All conformers are close to E0 or (0)E.
authors.affiliation: Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, PL-80-308 Gdańsk, Poland. Electronic address: andrzej.nowacki@ug.edu.pl.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Nowacki
authors.affiliation: Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, PL-80-308 Gdańsk, Poland.
authors.forename: Justyna
authors.initials: J
authors.lastname: Wielińska
authors.affiliation: Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, PL-80-308 Gdańsk, Poland.
authors.forename: Dominik
authors.initials: D
authors.lastname: Walczak
authors.affiliation: Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, PL-80-308 Gdańsk, Poland.
authors.forename: Karol
authors.initials: K
authors.lastname: Sikora
authors.affiliation: Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, PL-80-308 Gdańsk, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Dmochowska
authors.affiliation: Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, PL-80-308 Gdańsk, Poland.
authors.forename: Beata
authors.initials: B
authors.lastname: Liberek
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D004149:Dioxoles / Q000737:chemistry*; D005663:Furans / Q000737:chemistry*; D006860:Hydrogen Bonding; D007536:Isomerism; D008698:Mesylates / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D011789:Quantum Theory; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics
chemical_list: D000475:Alkenes; D004149:Dioxoles; D005663:Furans; D008698:Mesylates; D012997:Solvents
keywords: Conformation; DFT calculations; Furanoid ring; NBO; Quaternary ammonium salts