- 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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- 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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