- Isolation of an Antiaromatic Singlet Cyclopentadienyl Zwitterion
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The reaction of triplet tetrachlorocyclopentadienylidene with BF3 in rare gas matrices yields a zwitterion consisting of a cyclopentadienyl cation bearing a positive charge and a negatively charged BF3 unit. IR and UV-vis spectra as well as the absence of EPR signals demonstrate a singlet ground state of the zwitterion, and its calculated geometry and magnetic properties clearly reveal a strong antiaromatic character. The zwitterion is highly labile and by visible or IR irradiation rearranges via a 1,2-fluorine migration from boron to carbon. Interaction with a second molecule of BF3 stabilizes the zwitterion and suppresses the fluorine migration, thus providing a convenient and efficient synthesis of an antiaromatic molecule under very mild conditions.
- Costa, Paolo,Trosien, Iris,Mieres-Perez, Joel,Sander, Wolfram
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- Pentachlorocyclopentadienyl derivatives of manganese and rhodium
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Reaction of diazotetrachlorocyclopentadiene, I, with di-μ-chloro-bis(1,5-cyclooctadienerhodium), [RhCl(1,5-C8H12)]2, gives high yields of (η5-pentachlorocyclopentadienyl)(1,5-cyclooctadiene)rhodium, Rh(η5-C5Cl5)(COD), II. A similar reaction between I and pentacarbonylchloromanganese, MnCl(CO)5, gave two products: pentacarbonyl(η1-pentachlorocyclopentadienyl)manganese, Mn(η1-C5Cl5)(CO)5, III, and tricarbonyl(η5-pentachlorocyclopentadienyl)manganese, Mn(η5-C5Cl5)(CO)3, IV. III is the first transition metal complex containing a η1-C5Cl5- ring and for which there is no analog in C5H5--Mn chemistry. These compounds and other polychloro-substituted cyclopentadienyl complexes have been characterized by infrared, Raman, 13C nuclear magnetic resonance, and 35Cl nuclear quadrupole resonance spectroscopy. Qualitative results from investigations into the mechanism of the insertion reactions of diazocyclopentadienes into manganese-halogen bonds are discussed.
- Reimer, Kenneth J.,Shaver, Alan
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- INHIBITORS OF MTOR-DEPTOR INTERACTIONS AND METHODS OF USE THEREOF
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Provided herein are substituted hydrazone compounds useful as inhibitors of DEPTOR. The invention further provides pharmaceutical compositions of the compounds of the invention. The invention also provides medical uses of substituted hydrazone compounds.
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Page/Page column 34
(2018/05/24)
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- Structure-activity relationship study of small molecule inhibitors of the DEPTOR-mTOR interaction
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DEPTOR is a 48 kDa protein that binds to mTOR and inhibits this kinase within mTORC1 and mTORC2 complexes. Over-expression of DEPTOR specifically occurs in the multiple myeloma (MM) tumor model and DEPTOR knockdown is cytotoxic to MM cells, suggesting it is a potential therapeutic target. Since mTORC1 paralysis protects MM cells against DEPTOR knockdown, it indicates that the protein–protein interaction between DEPTOR and mTOR is key to MM viability vs death. In a previous study, we used a yeast two-hybrid screen of a small inhibitor library to identify a compound that inhibited DEPTOR/mTOR binding in yeast. This therapeutic (compound B) also prevented DEPTOR/mTOR binding in MM cells and was selectively cytotoxic to MM cells. We now present a structure–activity relationship (SAR) study around this compound as a follow-up report of this previous work. This study has led to the discovery of five new leads – namely compounds 3g, 3k, 4d, 4e and 4g – all of which have anti-myeloma cytotoxic properties superior to compound B. Due to their targeting of DEPTOR, these compounds activate mTORC1 and selectively induce MM cell apoptosis and cell cycle arrest.
- Lee, Jihye,Shi, Yijiang,Vega, Mario,Yang, Yonghui,Gera, Joseph,Jung, Michael E.,Lichtenstein, Alan
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p. 4714 - 4724
(2017/09/29)
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- Cyclopentadienylidenephosphinazines
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Diazocyclopentadienes which are not alkyl- or aryl-substituted at both the 2- and 5-positions react readily with triphenylphosphine to form cyclopentadienylidenephosphinazines. If both of these positions are so substituted phosphinazines are not formed. A phosphinazine was obtained from 2-chloro-3,4,5-triphenyldiazocyclopentadiene while its 2-nitro-analogue apparently formed a readily hydrolysed phosphinazine. Diazotetraphenylcyclopentadiene formed a phosphinazine with tri-n-butylphosphine. The reasons for these differences in reactivity are discussed. When heated to higher temperatures some of the phosphinazines decomposed with loss of nitrogen to give phosphonium cyclopentadienylides. Electron-withdrawing substituents in the five-membered ring make the phosphinazines susceptible to ready hydrolysis to cyclopentadienone hydrazones. Cyclopentadienylidenephosphinazines are protonated by mineral acids on nitrogen rather than on the cyclopentadiene ring.
- Freeman,Lloyd,Singer
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p. 211 - 216
(2007/10/13)
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