- Fluorescent deazaflavin - Oligonucleotide probes for selective detection of DNA
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Dramatic quenching of fluorescence is observed both in solution and on a glass surface during hybridization of deazaflavin - oligonucleotide conjugates (see picture, N = nucleoside) to a complementary strand. This opens up the possibility of a new type of
- Dueymes, Cecile,Decout, Jean Luc,Peltie, Philippe,Fontecave, Marc
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- Ruthenium-Pincer-Catalyzed Hydrogenation of Lactams to Amino Alcohols
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By using the commercially available ruthenium pincer complex (Ru-MACHO-BH) as a catalyst, the challenging direct hydrogenation of lactams and analogues has been successfully accomplished to deliver corresponding value-added amino alcohols in good-to-excellent yields under mild reaction conditions. Remarkably, in addition to N-protected lactams, unprotected ones could also be readily reduced in the presence of a catalytic amount of weak base or even under neutral reaction conditions, which further highlights the broad substrate scope and the protocol efficiency.
- Chen, Jiangbo,Wang, Jiaquan,Tu, Tao
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p. 2559 - 2565
(2018/07/30)
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- Efficient nickel-catalysed: N -alkylation of amines with alcohols
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The selective N-alkylation of amines with alcohols via the borrowing hydrogen strategy represents a prominent sustainable catalytic method, which produces water as the only by-product and is ideally suited for the catalytic transformation of widely available alcohol reaction partners that can be derived from renewable resources. Intensive research has been devoted to the development of novel catalysts that are mainly based on expensive noble metals. However, the availability of homogeneous or heterogeneous non-precious metal catalysts for this transformation is very limited. Herein we present a highly active and remarkably easy-to-prepare Ni based catalyst system for the selective N-alkylation of amines with alcohols, that is in situ generated from Ni(COD)2 and KOH under ligand-free conditions. This novel method is very efficient for the functionalization of aniline and derivatives with a wide range of aromatic and aliphatic alcohols as well as diols and exhibits excellent functional group tolerance including halides, benzodioxane and heteroaromatic groups. Several TEM measurements combined with elemental analysis were conducted in order to gain insight into the nature of the active catalyst and factors influencing reactivity.
- Afanasenko, Anastasiia,Elangovan, Saravanakumar,Stuart, Marc C. A.,Bonura, Giuseppe,Frusteri, Francesco,Barta, Katalin
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p. 5498 - 5505
(2018/11/20)
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- An Efficient and Selective Nickel-Catalyzed Direct N-Alkylation of Anilines with Alcohols
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Herein, we developed an efficient and selective nickel-catalyzed monoalkylation of various primary alcohols with aryl and heteroaryl amines together with diols and amino alcohol derivatives. Notably, the catalytic protocol consisting of an earth-abundant and non-precious NiBr2/L1 system enables the transformations in the presence of hydroxyl, alkene, nitrile, and nitro functionalities. As a highlight, we have demonstrated the alkylation of diamine, intramolecular cyclization to N-heterocycles, and functionalization of complex vitamin E, an (±)-α-tocopherol derivative. Preliminary mechanistic studies revealed the participation of a benzylic C-H bond in the rate-determining step.
- Vellakkaran, Mari,Singh, Khushboo,Banerjee, Debasis
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p. 8152 - 8158
(2017/12/08)
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- Catalytic hydrogenation of carboxamides and esters by well-defined Cp*Ru complexes bearing a protic amine ligand
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A novel catalytic method for the straightforward hydrogenation of carboxamides and esters to primary alcohols has been developed. Chiral modification in the ligand sphere of the well-defined Cp*Ru catalyst molecule opens up a new possibility for the development of an enantioselective hydrogenation of racemic substrates via dynamic kinetic resolution.
- Ito, Masato,Ootsuka, Takashi,Watari, Ryo,Shiibashi, Akira,Himizu, Akio,Ikariya, Takao
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supporting information; experimental part
p. 4240 - 4242
(2011/06/21)
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- Ruthenium-complex-catalyzed N-(Cyclo)alkylation of aromatic amines with diols. Selective synthesis of N-(ω-hydroxyalkyl)anilines of type PhNH(CH2)(n)OH and of some bioactive arylpiperazines
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A new class of well-defined neutral mono-, and dicationic ruthenium(II) complexes containing a neutral terdentate donor system [C5H3N(CH2E)2- 2,6] (E = PPh2 (PNP) or NME2 (NN'N) has been found effective as catalyst precursor in N-(cyclo)alkylation reactions of aromatic amines with diols Y(CH2CH2OH)2 (Y = CH2, NR). With these catalysts, N-phenylpiperidine is synthesized from aniline and 1,5-pentanediol in 85% yield (at 180 °C for 24 h in 1.4-dioxane). With neutral RuCl2(NN'N)-(PPh3) as a catalyst precursor, aniline can be selectively N-monoalkylated with diols of the type HO(CH2)(n)OH (n = 4-6, 10) to give N-(n-hydroxyalkyl)anilines in 40-75 yield. To our knowledge, this represents the first useful catalytic route to this type of compounds. The new catalysts can also be used in the synthesis of arylpiperazines. For example, N-phenyl-N'-methylpiperazine is obtained from aniline and MeN(CH2CH2OH)2 in yields up to 34%. N- [m(Trifluoromethyl)phenyl]-N'-methylpiperazine, TFMPMP, is successfully produced from m-(trifluoromethyl)aniline and MeN-(CH2CH2OH)2 in 44% yield using monocationic [RuOTf(NN'N)(PPh3)]OTf as the catalyst precursor. A mechanism for the N-(cyclo)alkylation reaction is proposed.
- Abbenhuis,Boersma,Van Koten
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p. 4282 - 4290
(2007/10/03)
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- A new synthetic route to macrocycles: Synthesis of large ring enaminolactones
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Macrocyclic enaminolactones 5 are prepared in three steps from commercially available chloroalcohols 1. The cyclization step is performed by intramolecular nucleophilic addition of the hydroxy group to an aminomethyleneketene generated by thermolysis.
- Jourdain,Pommelet
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p. 1545 - 1548
(2007/10/02)
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