- Chiral electron-rich PNP ligand with a phospholane motif: Structural features and application in asymmetric hydrogenation
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Despite the remarkable reactivity that was achieved by a series of transition-metal catalysts with a PNP type ligand, the electron-rich chiral PNP ligands have still been rarely reported because of the difficulties in synthesis and the nature of air-sensitivity. Herein, we report a novel chiral PNP ligand (Heng-PNP) with both a rigid backbone and a bulky tert-butyl group on the phospholane motif. We successfully obtained its divalent iron complex. The chiral environment of its Ir(III) complex was also discussed with quadrant analysis. This tridentate ligand was applied in iridium-catalyzed asymmetric hydrogenation of challenging diaryl ketones: up to 98% ee and 500 TON are achieved. Computational study showed that the twist of conjugate aryl group in the substrate (induced by the special chiral pocket of Ir/Heng-PNP complex) leads to the energy difference in the enantiodetermining step.
- Wang, Heng,Zhang, Yao,Yang, Tilong,Guo, Xiaochong,Gong, Quan,Wen, Jialin,Zhang, Xumu
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supporting information
p. 8796 - 8801
(2020/11/13)
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- NMO·TPB: A selectivity variation on the Ley-Griffith TPAP oxidation
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A non-hygroscopic tetraphenylborate salt of N-methylmorpholine-N-oxide (NMO) is reported (NMO·TPB), which modulates the standard Ley-Griffith oxidation such that benzylic and allylic alcohols are oxidised selectively. An attractive feature of this new protocol is that anhydrous conditions are not required for this selective tetra-n-propylammonium perruthenate (TPAP) oxidation, superseding the requirement of molecular sieves.
- Moore, Peter W.,Mirzayans, Paul M.,Williams, Craig M.
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p. 3567 - 3571
(2015/03/04)
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- Bu4N+ alkoxide-initiated/autocatalytic addition reactions with organotrimethylsilanes
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The use of Me3SiO-/Bu4N+ as a general activator of organotrimethylsilanes for addition reactions has been established. The broad scope of the method offers trimethylsilanes (including acetate, allyl, propargyl, benzyl, dithiane, heteroaryl, and aryl derivatives) as bench-stable organometallics that can be readily utilized as carbanion equivalents for synthesis. Reactions are achieved at rt without the requirement of specialized precautions that are commonplace for other organometallics.
- Das, Manas,O'Shea, Donal F.
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p. 5595 - 5607
(2014/07/08)
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- From in vitro to in cellulo: Structure-activity relationship of (2-nitrophenyl)methanol derivatives as inhibitors of PqsD in Pseudomonas aeruginosa
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Recent studies have shown that compounds based on a (2-nitrophenyl)methanol scaffold are promising inhibitors of PqsD, a key enzyme of signal molecule biosynthesis in the cell-to-cell communication of Pseudomonas aeruginosa. The most promising molecule displayed anti-biofilm activity and a tight-binding mode of action. Herein, we report on the convenient synthesis and biochemical evaluation of a comprehensive series of (2-nitrophenyl)methanol derivatives. The in vitro potency of these inhibitors against recombinant PqsD as well as the effect of selected compounds on the production of the signal molecules HHQ and PQS in P. aeruginosa were examined. The gathered data allowed the establishment of a structure-activity relationship, which was used to design fluorescent inhibitors, and finally, led to the discovery of (2-nitrophenyl)methanol derivatives with improved in cellulo efficacy providing new perspectives towards the application of PqsD inhibitors as anti-infectives. This journal is the Partner Organisations 2014.
- Storz, Michael P.,Allegretta, Giuseppe,Kirsch, Benjamin,Empting, Martin,Hartmann, Rolf W.
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supporting information
p. 6094 - 6104
(2014/08/05)
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- Structure-activity relationships of diphenylpiperazine N-type calcium channel inhibitors
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A novel series of compounds derived from the previously reported N-type calcium channel blocker NP118809 (1-(4-benzhydrylpiperazin-1-yl)-3,3-diphenylpropan-1-one) is described. Extensive SAR studies resulted in compounds with IC50 values in the range of 10-150 nM and selectivity over the L-type channels up to nearly 1200-fold. Orally administered compounds 5 and 21 exhibited both anti-allodynic and anti-hyperalgesic activity in the spinal nerve ligation model of neuropathic pain.
- Pajouhesh, Hassan,Feng, Zhong-Ping,Ding, Yanbing,Zhang, Lingyun,Pajouhesh, Hossein,Morrison, Jerrie-Lynn,Belardetti, Francesco,Tringham, Elizabeth,Simonson, Eric,Vanderah, Todd W.,Porreca, Frank,Zamponi, Gerald W.,Mitscher, Lester A.,Snutch, Terrance P.
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scheme or table
p. 1378 - 1383
(2010/07/06)
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- Highly efficient and facile aryl transfer to aldehydes using ArB(OH) 2-GaMe3
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A rapid and efficient procedure for the synthesis of diarylmethanols has successfully been achieved by the aryl transfer to aldehydes using the ArB(OH)2-GaMe3 combined systems in excellent yields (up to 98%) at room temperature. Georg Thieme Verlag Stuttgart.
- Jia, Xuefeng,Fang, Ling,Lin, Aijun,Pan, Yi,Zhu, Chengjian
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body text
p. 495 - 499
(2009/09/08)
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- Microwave irradiation as a high-speed tool for activation of sluggish aryl chlorides in Grignard reactions
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Grignard reagents have been generated from reluctant aryl chlorides and bromides using controlled microwave heating to establish a safe, productive and reproducible method. In the synthesis of a novel HIV-1 protease inhibitor, microwave irradiation was both used to generate the starting arylmagnesium halide and to promote a subsequent Kumada coupling. Georg Thieme Verlag Stuttgart.
- Gold, Henrik,Larhed, Mats,Nilsson, Peter
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p. 1596 - 1600
(2007/10/03)
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- AZETIDINECARBOXAMIDE DERIVATIVES AND THEIR USE IN THE TREATMENT OF CB1 RECEPTOR MEDIATED DISORDERS
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Compounds of formula (I) and their use in therapy, particularly for the treatment of a disorder mediated by CB1 receptors such as obesity: Formuila (I) wherein: R1 and R2 are independently selected from aryl; and R3 is hydrogen or alkyl; or a pharmaceutically acceptable salt or prodrug thereof, wherein at least one of R1 and R2 has a non-hydrogen substituent in the ortho-position(s) thereof relative to the point of attachment to the [-CH-0-] group.
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- Preparation of organomanganese reagents from organic halides with activated manganese
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Reduction of Li2MnCl4 with magnesium metal provided activated manganese as a black suspension in THF. Treatment of organic halides such as allyl bromides, α-halo esters or aryl halides with activated manganese furnished various organomanganese reagents which reacted further with electrophiles to afford the corresponding adducts. The reaction of a ketone bearing an iodoaryl moiety with this active manganese induced cyclization to provide dihydroindene derivative.
- Kakiya, Hirotada,Nishimae, Shinji,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 8807 - 8815
(2007/10/03)
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- Preparation of allyl-, alkenyl- and of functionalized arylmanganese reagents by oxidative insertion of manganese-graphite into organic halides
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Reduction of MnBr2·nLiBr (n = 1,2) with 2 C8K in THF affords highly active Mn-graphite, which readily insert into allyl-, alkenyl-, (substituted) aryl- and heteroaryl halides. The functionalized organomanganese compounds thus obtained may be efficiently trapped with different electrophiles such as aldehydes, anhydrides and acid chlorides, or can be cross-coupled with alkenyl halides in the presence of catalytic amounts of Fe(acac)3.
- Fuerstner, Alois,Brunner, Heiko
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p. 7009 - 7012
(2007/10/03)
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- Determination of the Enantiomeric Excesses of Chiral Acids by 19F NMR Studies of their Esters deriving from (R)-(+)-2-(Trifluoromethyl)benzhydrol
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15-Chiral acids were esterified with optically pure (R)-(+)-2-(trifluoromethyl)benzhydrol (R)-(+)-1, a readily available reagent.With respect to the carboxy group, the stereogenic centre is in the β-position in the case of the acids 5a-10a and 12a-16a, and in the α position in the case of the acids 17a-20a.The diastereomeric excesses of the corresponding esters 5b-10b and 12b-20b, respectively, were easily determined by means of 19F NMR.These d.e. values were in very good agreement with the e.e. values of the corresponding acids when the latter were known compounds.
- Brown, Eric,Chevalier, Christelle,Huet, Francois,Grumelec, Christelle Le,Leze, Antoine,Touet, Joel
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p. 1191 - 1194
(2007/10/02)
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- Comparative Mechanistic Study of the Reaction of Benzophenone with n-BuMgBr and n-BuLi
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Substituent effects on reactivity and product distribution (addition vs reduction) were determined for the reactions of benzophenones with n-BuMgBr and n-BuLi at 0 deg C.In case of the reaction with n-BuMgBr, meta and para-substituted benzophenones gave a reasonably linear Hammet plot, from which the ρ value of 1.45 was calculated, while ortho-substituted derivatives deviated downward from the correlation line.In contrast, the reaction with n-BuLi exhibit very small substituent effects on reactivity.The product distrubution is highly dependent on substituents in the n-BuMgBr reaction, whereas it is essentially independent of substituents in the n-BuLi reaction.Mechanistic differences between the reactions of these two reagents are discussed on the basis of these experimental results.
- Yamataka, Hiroshi,Miyano, Nobutaka,Hanafusa, Terukiyo
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p. 2573 - 2575
(2007/10/02)
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