- [2+2+2]-Cycloaddition of 4-Hydroxy-Substituted Enediynes to 2-Hydroxy-Substituted Decahydrophenanthrenes
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Enediynes rac-4 were prepared in seven steps with an overall yield of 31% starting from 4-pentyn-1-ol (5). A cobalt mediated [2+2+2]-cycloaddition of these enediynes and subsequent removal of the metal fragment afforded the decahydrophenanthrenes rac-3/13
- Groth, Ulrich,Richter, Norbert,Kalogerakis, Aris
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- Synthesis of Tetrasubstituted Alkenes by Tandem Metallacycle Formation/Cross-Electrophile Coupling
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Nickel-catalyzed cross-electrophile couplings have recently emerged as highly effective and practical methods for the formation of C-C bonds. By merging this process with well-established π-π coupling chemistry, a new method for the synthesis of tetrasubstituted alkenes has been developed. The procedure relies on the use of chlorosilanes as a means of generating reactive vinylnickel intermediates, which are capable of undergoing a reductive cross-electrophile coupling with alkyl halides. The method not only generates highly substituted allylic alcohol derivatives but also obviates the need for stoichiometric organometallic nucleophiles and provides greatly improved scope and functional group tolerance compared with previously developed methods.
- Shimkin, Kirk W.,Montgomery, John
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supporting information
p. 7074 - 7078
(2018/06/04)
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- A generalizable platform for interrogating target- and signal-specific consequences of electrophilic modifications in redox-dependent cell signaling
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Despite the known propensity of small-molecule electrophiles to react with numerous cysteine-active proteins, biological actions of individual signal inducers have emerged to be chemotype-specific. To pinpoint and quantify the impacts of modifying one target out of the whole proteome, we develop a target-protein-personalized "electrophile toolbox" with which specific intracellular targets can be selectively modified at a precise time by specific reactive signals. This general methodology, T-REX (targetable reactive electrophiles and oxidants), is established by (1) constructing a platform that can deliver a range of electronic and sterically different bioactive lipid-derived signaling electrophiles to specific proteins in cells; (2) probing the kinetics of targeted delivery concept, which revealed that targeting efficiency in cells is largely driven by initial on-rate of alkylation; and (3) evaluating the consequences of protein-target- and small-molecule-signal-specific modifications on the strength of downstream signaling. These data show that T-REX allows quantitative interrogations into the extent to which the Nrf2 transcription factor-dependent antioxidant response element (ARE) signaling is activated by selective electrophilic modifications on Keap1 protein, one of several redox-sensitive regulators of the Nrf2-ARE axis. The results document Keap1 as a promiscuous electrophile-responsive sensor able to respond with similar efficiencies to discrete electrophilic signals, promoting comparable strength of Nrf2-ARE induction. T-REX is also able to elicit cell activation in cases in which whole-cell electrophile flooding fails to stimulate ARE induction prior to causing cytotoxicity. The platform presents a previously unavailable opportunity to elucidate the functional consequences of small-molecule-signal- and protein-target-specific electrophilic modifications in an otherwise unaffected cellular background.
- Lin, Hong-Yu,Haegele, Joseph A.,Disare, Michael T.,Lin, Qishan,Aye, Yimon
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supporting information
p. 6232 - 6244
(2015/06/02)
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- Aminoalkynyldithianes. A new class of calcium channel blockers
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Several dithiane derivatives, prepared as intermediates for compounds structurally related to the therapeutically useful antimuscarinic agent oxybutynin, were effective inhibitors of calcium ion induced contraction of guinea pig ileal strips and of KCl-in
- Adams,Dupont,Carter,Kachur,Guzewska,Rzeszotarski,Farmer,Noronha-Blob,Kaiser
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p. 1585 - 1593
(2007/10/02)
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