TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Ushakov, Igor A.
A1  - Meshcheryakov, Vladimir I.
A1  - Schilde, Uwe
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
T1  - The stereodynamics of 3,5-bis(trifluoromethylsulfonyl)-1,3,5-oxadiazinane and 1,3,5- tris(trifluoromethylsulfonyl)-1,3,5-triazinane- an experimental and theoretical study
N2  - Multinuclear dynamic NMR spectroscopy of 3,5-bis(trifluoromethylsulfonyl)-1,3,5-oxadiazinane (3) revealed the existence of two conformers with differently oriented CF3 groups with respect to the ring, and two dynamic processes: ring inversion and restricted rotation about the N-S bond. Two transition states connecting the two conformers and corresponding to clockwise and counterclockwise rotations about the N-S bond were found; the calculated activation barriers of about 12 kcal/mol are in excellent agreement with those measured experimentally for the related molecule 1,3,5-tris(trifluoromethylsulfonyl)-1,3,5-triazinane (1). X-ray analysis proved the existence of the symmetric isomer of 3, which is the minor isomer in solutions but the only one in the crystal due to packing effects. The normal Perlin effect (JCHax < JCHeq)observed for 2(6)-CH2 in 3, whereas the reversed Perlin effect was found for the 4-CH2 group in 3 as well as for all CH2 groups in 1 both experimentally and theoretically. The latter effect in compounds 1, 3, and 1- (methylsulfonyl)-3,5-bis(trifluoromethylsulfonyl)-1,3,5-triazinane (2) can be considered as a genuine reverse Perlin effect since larger values of 1JCH are observed for longer C-H bonds.
Y1  - 2007
UR  - http://www.sciencedirect.com/science/article/pii/S0040402007016389
U6  - https://doi.org/10.1016/j.tet.2007.09.041
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Ushakov, Igor A.
A1  - Meshcheryakov, Vladimir I.
A1  - Koch, Andreas
A1  - Kleinpeter, Erich
T1  - Variable temperature NMR and theoretical study of the stereodynamics of 5-trifluoromethylsulfonyl-1,3,5- dioxaazinane : Perlin effect subject to heteroatom substitution
N2  - Multinuclear dynamic NMR spectroscopy of 5-trifluoromethylsulfonyl-1,3,5-dioxaazinane (4) revealed the existence of two close in energy chair conformers with differently oriented CF3 groups with respect to the ring. Of the two alternative routes for their interconversion, the ring inversion path with intermediate formation of the corresponding 2,5-twist-conformer is preferred, with the energy barrier of 11.2 kcal/mol in excellent agreement with the experimental value (11.7 kcal/mol). The Perlin effect is studied experimentally and calculated theoretically for all CH2 groups and found to be subject to the nature of the adjacent heteroatoms O and N, respectively.
Y1  - 2008
ER  - 
TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Meshcheryakov, Vladimir I.
A1  - Sterkhova, I. V.
A1  - Kelling, Alexandra
A1  - Schilde, Uwe
T1  - Structure of the molecule of 1,2-bis(1-ethyl-1 H -1,2,3-triazol-4-yl)diazene 1-oxide in the crystal and in solutions
N2  - Reduction of 4-nitro-1-ethyl-1H-1,2,3-triazole with aluminum in alkaline medium resulted in a syn-isomer of 1,2- bis(1-ethyl-1H-1,2,3-triazol-4-yl)diazene 1-oxide. The latter according to the data of X-ray diffraction analysis existed in the crystal as the most stable s-cis,s-trans-conformer, and in solution, as showed NMR data, as a mixture of s-cis,s-trans- and s-trans,s-trans-conformers. The data of quantum-chemical calculations are in agreement with the results of the structural studies.
Y1  - 2008
UR  - http://springer.metapress.com/content/p210730742rh4117/
SN  - 1070-4280
ER  - 
TY  - JOUR
A1  - Meshcheryakov, Vladimir I.
A1  - Moskalik, Mikail Yu.
A1  - Kelling, Alexandra
A1  - Schilde, Uwe
A1  - Ushakov, Igor A.
A1  - Shainyan, Bagrat A.
T1  - Oxymethylation of trifluoromethanesulfonamide with paraformaldehyde in ethyl acetate
N2  - Acid-catalyzed reaction of trifluoromethanesulfonamide with paraformaldehyde in ethyl acetate led to the formation of oxymethylated products that did not form in the reaction carried out in sulfuric acid. Following products were obtained: 5-trifluoromethylsulfonyl-1,3-dioxazinane, 3,7-bis-(trifluoromethylsulfonyl)-1,5,3,7-dioxadiazocane, and a complex of trifluoromethanesulfonamide with 2,4,8,10-tetraoxospiro[5,5]undecene, 1:1. The spiroring resulted from the cyclization of pentaerythritol under the action of formaldehyde. The pentaerythritol formed in its turn by oxymethylation of the methyl group of ethyl acetate with paraformaldehyde followed by the reduction of the COOEt group into CH2 OH by the formaldehyde.
Y1  - 2008
UR  - http://springer.metapress.com/content/q58m84577ng74p3g/ ?p=0be1219998b44c288f855f33f6168bf6&pi=19
U6  - https://doi.org/10.1134/S1070428008020206
SN  - 1070-4280
ER  -