- Murai Reaction on Furfural Derivatives Enabled by Removable N,N′-Bidentate Directing Groups
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Furfural and related compounds are industrially relevant building blocks obtained from lignocellulosic biomass. To enhance the added value of these renewable resources, a Ru-catalyzed hydrofurylation of alkenes, involving a directed C?H activation at C3 of the furan ring, was developed. A thorough experimental study revealed that a bidentate amino-imine directing group enabled the desired coupling. Removal of the directing group occurred during the purification step, directly releasing the C3-functionalized furfurals. Development of the reaction as well as optimization and scope of the method were described. A mechanism was proposed on the basis of DFT calculations.
- Pezzetta, Cristofer,Veiros, Luis F.,Oble, Julie,Poli, Giovanni
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p. 8385 - 8389
(2017/06/28)
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- Reversal agent and linker variants of reversed chloroquines: Activities against Plasmodium falciparum
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We have shown that "reversed chloroquine molecules" constructed from chloroquine-like and resistance "reversal-agent"-like cores can be powerful drugs against malaria (J. Med. Chem. 2006, 49, 5623-5625). Several reversed chloroquines are now presented that probe parameters governing the activities against chloroquine-resistant and chloroquine-sensitive malaria strains. The design is tolerant to linker and reversal agent changes, but a piperazinyl group adjacent to the quinoline, at least for the group of compounds studied here, may be detrimental. 2009 American Chemical Society.
- Andrews, Simeon,Burgess, Steven J.,Skaalrud, Deborah,Kelly, Jane Xu,Peyton, David H.
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supporting information; experimental part
p. 916 - 919
(2010/07/05)
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- 5-(2-Aminoethyl)dibenzo[c,h][1,6]naphthyridin-6-ones: Variation of N-alkyl substituents modulates sensitivity to efflux transporters associated with multidrug resistance
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5H-8,9-Dimethoxy-5-(2-N,N-dimethylaminoethyl)-2,3-methylenedioxydibenzo[c, h]-[1,6]naphthyridin-6-one (ARC-111) has potent TOP1-targeting activity and pronounced antitumor activity. Several analogues of ARC-111 were synthesized with NH2, N-alkyl, N,N-dialkyl, pyrrolidinyl, piperidinyl, and piperazinyl substituents at the 2-position of the 5-ethyl group. The relative TOP1-targeting activity and cytotoxicity of these structural analogues were assessed in RPMI8402 and P388 tumor cells and their camptothecin-resistant variants CPT-K5 and P388/CPT45, respectively. Potent TOP1-targeting activity was retained within a series of mono N-alkyl analogues that included NHCH 2CH3, NHCH(CH3)2, and NHC(CH 3)3. TOP1-targeting activity was diminished by the presence of a N-benzyl moiety. In a comparison of a series of N-alkyl-N-isopropyl analogues, activity decreased in the order CH3 > CH2CH3 > CH-(CH3)2. Cytotoxicity in RPMI8402 and P388 did correlate with TOP1-targeting activity. Cytotoxic activity was also determined in KB3-1 cells and its variants KB/V-1 and KBH5.0. As KB/V-1 cells overexpress MDR1 and KBH5.0 cells overexpress BCRP, decreased cytotoxicity in these cell lines relative to the parent cell line is indicative of compounds that are substrates for these efflux transporters. In view of their diminished cytotoxicity in KB/V-1 cells, it appears that the likely demethylated metabolites of ARC-111, i.e., where NH2 or NHCH3 replaces the N(CH3)2 at the 2-position of the 5-ethyl substituent, are substrates for MDR1. In contrast, no significant difference in cytotoxicity among these three cell lines was observed with other N-alkyl analogues, including NHC2H5, NHCH(CH 3)2, NHC(CH3)3, N(CH 3)2, N(CH2CH3)2, NCH 3(CH-(CH3)2), and either the pyrrolidinyl or the piperidinyl analogues. The 2-(piperazinyl) analogues were associated with diminished cytotoxicity in KB/V-1 cells, suggesting that the second basic amino substituent is associated with their recognition as substrates by MDR1. Comparative studies on the antitumor activity of ARC-111 and its N-demethylated derivatives (the NHCH3 and NH2 analogues) against SJ-BT45 medulloblastoma xenografts in seid mice revealed that the secondary amine metabolite is at least as active as ARC-111 in vivo, although the primary amine derivative was significantly less potent.
- Ruchelman, Alexander L.,Houghton, Peter J.,Zhou, Nai,Liu, Angela,Liu, Leroy F.,LaVoie, Edmond J.
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p. 792 - 804
(2007/10/03)
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