Specific Molecular Orbital Contributions to Nucleophilicity. The Thiocarbonyl Group as Priviledged Monitor to Pinpoint Active and Less Active Molecular Orbitals in Reactions with Methylating Agents
摘要:
The rate constants for 41 compounds bearing a C=S function reacting with MeX (X = I, Tos) span 7 orders of magnitude. The PES spectra of these compounds display two very low energy peaks, which stand clearly apart from the other peaks. These two peaks correspond to the pi orbitals of the C-S group; one is its CS pi bonding orbital oriented out of the molecular plane (pi(CS)) and the other its p-type in-plane lone pair orbital (pi(S)). For some of the compounds, the HOMO is the pi(CS) orbital and for others the HOMO is the ns lone pair orbital. The best correlation (R = 0.96) between rate constants h and PES data is obtained when In(k) is plotted against the inverse of PES energy of the pi(S) lone pair orbital. Whether this lone pair orbital is the HOMO or the next lower HOMO has no importance. A modest correlation (R = 0.78) is obtained when In(k) is plotted against the inverse of PES energy of the pi(CS) bonding orbital, An attempt to correlate the calculated energy of the third highest occupied orbital (from AM1 calculations) with In(h) provides a complete scattering of data (R < 0.1), but the calculated energy of the second lone pair orbital sigma(S) (approximate to 90 kcal mol-l deeper than the HOMO) correlates reasonably with In(h) (R = 0.88). The energies of the S 2s and 2p core orbitals (calculated for 13 cyclic compounds with the HF/3-21G technique to be 4000 to 5500 kcal mol(-1) deeper than HOMO) correlate with In(k) (R = 0.86) as well as does that of the second lone pair orbital os. These results are the first where both frontier orbitals and core orbitals display correlation with overall reactivity. They are discussed in terms of direct (perturbational) versus indirect (nonperturbational) concepts.
2,4-Dihydro-3H-1,2,4-triazole-3-thiones as potential antidepressant agents
作者:John M. Kane、Mark W. Dudley、Stephen M. Sorensen、Francis P. Miller
DOI:10.1021/jm00401a031
日期:1988.6
prepared and evaluated for potentialantidepressant activity. Members of this series were generally prepared by the alkaline ring closures of the corresponding 1-aroylthiosemicarbazides. Several members of this series were potent antagonists of both RO 4-1284-induced hypothermia and reserpine-induced ptosis in mice. In general the more active members of this series were substituted by haloaryl groups at
The Bis(tricyclohexylstannyl) Sulfide Thionation of 3<i>H</i>-1,2,4- Triazol-3-ones
作者:John M. Kane
DOI:10.1055/s-1987-28119
日期:——
5-Aryl-2,4-dialkyl-2,4-dihydro-3H-1,2,4-triazol-3-ones may be converted in 55-74% yield to the corresponding 3H-1,2,4-triazole-3-thiones by using the combination bis(tricyclohexylstannyl) sulfide/boron trichloride.
Process for the preparation of 5-aryl-2,4-dialkyl-3H-1,2,4-triazole-3-thiones
申请人:MERRELL DOW PHARMACEUTICALS INC.
公开号:EP0280867A1
公开(公告)日:1988-09-07
This invention relates to a novel process for the preparation of 5-aryl-2,4-dialkyl-3H-1,2,4-triazole-3-thiones, useful as antidepressants, through the thionation of the corresponding 5-aryl-2,4-dialkyl-3H-1,2,4-triazol-3-ones.
led to the formation of the 1,2,4-triazoline-5-thione ring and to the 1,2,4-triazolium-5-thiolate ring. The formation of the mesoionic componds is due to rearrangement of the easily available 2,4-disubstituted thiosemicarbazides to 1,4-disubstituted thiosemicarbazides under the reaction conditions adopted. This method can be usefully used for the synthesis of mesoionic compounds, especially in the case
5-aryl-4-alkyl-3H-1,2,4-triazole-3-thiones useful as memory enhancers
申请人:MERRELL PHARMACEUTICALS INC.
公开号:EP0452926A2
公开(公告)日:1991-10-23
This invention relates to the enhancement of memory and cognition and the treatment of Alzheimer's disease and Wernicke-Korsakoff syndrome by 5(Rn-phenyl)-4-alkyl-3H-1,2,4-triazole-3-thiones of the formula
wherein
Ris halogen, trifluoromethyl, C₁₋₄ lower alkyl or C₁₋₄ lower alkoxy,
nis zero, 1 or 2, and
R₂represents hydrogen or C₁₋₃ lower alkyl; and
R₄independently represents C₁₋₃ lower alkyl .