TY - JOUR
T1 - Conformationai analysis of naphtho[1,8-b,c]-1,5-dithiocin and its s-oxides in solution
AU - Glass, Richard S.
AU - Broeker, Jeffrey L.
PY - 1991
Y1 - 1991
N2 - The conformation and conformational barriers In dithioether 1: naphtho(1,8-b,c]-1,5-dithiocin were determined in solution by 1H and 13C NMR spectroscopic analysis and AMl semiempirical computations. In solution the chair conformer of dithloether 1 is 0.6 kcal/mol lower in energy than the boat conformer. The barriers for chair-to-chair ring inversion and chair-to-boat conversion in this compound are 8.9 kcal/mol and 7.9 kcal/mol, respectively. Monosulfone 3, disulfoxide 4, and sulfoxide-sulfone 5, adopt the chair conformation in solution in contrast to their boat conformation in the solid state. In solution the chair conformation for 3-5 with equatorial sulfoxides is more stable than either the chair conformation with axial sulfoxides or the boat conformers by at least 1 kcal/mol. The barrier for chair-to-chair ring inversion for monosulfone 3 has been determined to be 10.8 kcal/mol. In solution, disulfone 6 appears to adopt either a boat or chair conformation in contrast to the twist conformation in the solid state. The maximum barrier for ring inversion of 6 is 7 kcal/mol. New evidence for the geometry of the transition state for the ring inversion is presented.
AB - The conformation and conformational barriers In dithioether 1: naphtho(1,8-b,c]-1,5-dithiocin were determined in solution by 1H and 13C NMR spectroscopic analysis and AMl semiempirical computations. In solution the chair conformer of dithloether 1 is 0.6 kcal/mol lower in energy than the boat conformer. The barriers for chair-to-chair ring inversion and chair-to-boat conversion in this compound are 8.9 kcal/mol and 7.9 kcal/mol, respectively. Monosulfone 3, disulfoxide 4, and sulfoxide-sulfone 5, adopt the chair conformation in solution in contrast to their boat conformation in the solid state. In solution the chair conformation for 3-5 with equatorial sulfoxides is more stable than either the chair conformation with axial sulfoxides or the boat conformers by at least 1 kcal/mol. The barrier for chair-to-chair ring inversion for monosulfone 3 has been determined to be 10.8 kcal/mol. In solution, disulfone 6 appears to adopt either a boat or chair conformation in contrast to the twist conformation in the solid state. The maximum barrier for ring inversion of 6 is 7 kcal/mol. New evidence for the geometry of the transition state for the ring inversion is presented.
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U2 - 10.1016/S0040-4020(01)87121-0
DO - 10.1016/S0040-4020(01)87121-0
M3 - Article
AN - SCOPUS:0025872453
VL - 47
SP - 5087
EP - 5098
JO - Tetrahedron
JF - Tetrahedron
SN - 0040-4020
IS - 28
ER -