TY  - JOUR
A1  - Shainyan, Bagrat A.
A1  - Kleinpeter, Erich
T1  - Conformational flexibility of 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline and its monoheterocyclic analogs
JF  - Russian journal of general chemistry
N2  - Conformational behavior of the first cyclic organosilicon vinylsulfide, 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline as well as its monoheterocyclic analogs, 3,4-dihydro-2H-pyran, 3,4-dihydro-2H-thiopyran, and 1,1-dimethyl-1,2,3,4-tetrahydrosiline is studied in comparison with the carbocyclic analog, cyclohexene, using the methods of low-temperature NMR spectroscopy and theoretical calculations at the DFT and MP2 levels of theory. The barrier to the ring inversion with respect to that in cycloxene is increased in 3,4-dihydro-2H-pyran and 1,1-dimethyl-1,2,3,4-tetrahydrosiline, but, in contrast to the suggestions made in the literature, is decreased in 3,4-dihydro-2H-thiopyran. In 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline the barrier is intermediate between those in the corresponding monoheterocycles, 1,1-dimethyl-1,2,3,4-tetrahydrosiline and 3,4-dihydro-2H-thiopyran. The observed variations are rationalized from the viewpoint of the interaction of the pi-electrons of the C=C double bond with the orbitals of heteroatoms in the ring. The structure of the transition state for the ring inversion is discussed.
KW  - 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline
KW  - 1,1-dimethyl-1,2,3,4-tetrahydrosiline
KW  - 3,4-dihydro-2H-thiopyran
KW  - 3,4-dihydro-2H-pyran
KW  - onformational analysis
Y1  - 2014
U6  - https://doi.org/10.1134/S1070363214070135
SN  - 1070-3632
SN  - 1608-3350
VL  - 84
IS  - 7
SP  - 1325
EP  - 1329
PB  - Pleiades Publ.
CY  - New York
ER  -