- Molecularly Defined Manganese Pincer Complexes for Selective Transfer Hydrogenation of Ketones
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For the first time an easily accessible and well-defined manganese N,N,N-pincer complex catalyzes the transfer hydrogenation of a broad range of ketones with good to excellent yields. This cheap earth abundant-metal based catalyst provides access to useful secondary alcohols without the need of hydrogen gas. Preliminary investigations to explore the mechanism of this transformation are also reported.
- Perez, Marc,Elangovan, Saravanakumar,Spannenberg, Anke,Junge, Kathrin,Beller, Matthias
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- Development of an Expedient Process for the Multi-Kilogram Synthesis of Chk1 Inhibitor GDC-0425
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A process leading to the multikilogram GMP synthesis of Chk1 inhibitor GDC-0425 (1) was developed. Highlights of the synthesis include protection of the pyrrole ring of a 1,7-diazacarbazole as propyl ethyl ether, an efficient Pd catalyzed cyanation of an aryl chloride, aryl ether formation by SNAr fluoride displacement, and development of a controlled crystallization providing the API with the required polymorphic form. The process delivered high-quality GDC-0425 with low levels of impurities and residual metals in five steps and 31% overall yield.
- Stumpf, Andreas,Cheng, Zhigang Ken,Wong, Brian,Reynolds, Mark,Angelaud, Remy,Girotti, James,Deese, Alan,Gu, Christine,Gazzard, Lewis
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supporting information
p. 661 - 672
(2015/06/30)
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- Selective N-alkylation of amines using nitriles under hydrogenation conditions: Facile synthesis of secondary and tertiary amines
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Nitriles were found to be highly effective alkylating reagents for the selective N-alkylation of amines under catalytic hydrogenation conditions. For the aromatic primary amines, the corresponding secondary amines were selectively obtained under Pd/C-catalyzed hydrogenation conditions. Although the use of electron poor aromatic amines or bulky nitriles showed a lower reactivity toward the reductive alkylation, the addition of NH4OAc enhanced the reactivity to give secondary aromatic amines in good to excellent yields. Under the same reaction conditions, aromatic nitro compounds instead of the aromatic primary amines could be directly transformed into secondary amines via a domino reaction involving the one-pot hydrogenation of the nitro group and the reductive alkylation of the amines. While aliphatic amines were effectively converted to the corresponding tertiary amines under Pd/C-catalyzed conditions, Rh/C was a highly effective catalyst for the N-monoalkylation of aliphatic primary amines without over-alkylation to the tertiary amines. Furthermore, the combination of the Rh/C-catalyzed N-monoalkylation of the aliphatic primary amines and additional Pd/C-catalyzed alkylation of the resulting secondary aliphatic amines could selectively prepare aliphatic tertiary amines possessing three different alkyl groups. According to the mechanistic studies, it seems reasonable to conclude that nitriles were reduced to aldimines before the nucleophilic attack of the amine during the first step of the reaction.
- Ikawa, Takashi,Fujita, Yuki,Mizusaki, Tomoteru,Betsuin, Sae,Takamatsu, Haruki,Maegawa, Tomohiro,Monguchi, Yasunari,Sajiki, Hironao
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supporting information; experimental part
p. 293 - 304
(2012/02/01)
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- Design, synthesis and biological evaluation of a novel series of potent, orally active adenosine A1 receptor antagonists with high blood-brain barrier permeability
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A novel series of 3-(2-substituted-3-oxo-2,3-dihydropyridazin-6-yl) -2-phenylpyrazolo[1,5-a]pyridines (5-38) were synthesized and evaluated for their in vitro adenosine A1 and A2A receptor binding activities, and in vitro metabolism by rat liver in order to search for orally active compounds. Most of the test compounds were potent adenosine A1 receptor antagonists with high A1 selectivity and the A1 affinity and A1 selectivity of carbonyl derivatives (5-11) was particularly high. In particular, compound 7 was an extremely potent and selective adenosine A1 antagonist with high A1 selectivity (Ki=0.026 nM, A2A/A1=5400). In terms of metabolic stability, 2-oxopropyl (5), 2-hydroxypropyl (12), N-methylacetamide (16), 2-(piperidin-1-yl)ethyl (28) and 1-methylpiperidin-4-yl (32, FR194921) were the most stable compounds in this series of analogues. Further in vivo evaluation indicated that compounds 5, 13, 17, 28 and 32 were detected in both plasma and brain after oral administration in rats. In particular, 32 displayed good plasma and brain concentrations (dose: 32mg/kg (n=3); after 30 min, plasma conc.=3390±651 nM, brain conc.=3670±496 nM; after 60 min, plasma conc.=1580±348 nM, brain conc.=2143±434 nM), and a good brain/plasma ratio (1.11±0.060 (30 min), 1.39±0.172 (60 min)). As a result, we could show that 32 is a good candidate for an orally active adenosine A1 receptor antagonist with high blood-brain barrier permeability and good bioavailability (Ki=6.6 nM, A2A/A1=820, BA=60.6±4.9% (32 mg/kg)).
- Kuroda,Takamura,Tenda,Itani,Tomishima,Akahane,Sakane
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p. 988 - 998
(2007/10/03)
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