- Transesterification of α-amino esters catalyzed by a tetranuclear zinc cluster: Zn4(OCOCF3)6O
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Transesterification of amino acid ester derivatives was developed using a tetranuclear zinc cluster, Zn4(OCOCF3)6O, as the catalyst. Because the reaction conditions were very mild, a variety of N-protective groups and functional groups on side chains were tolerated. Georg Thieme Verlag Stuttgart. New York.
- Maegawa, Yusuke,Agura, Kazushi,Hayashi, Yukiko,Ohshima, Takashi,Mashima, Kazushi
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supporting information; experimental part
p. 137 - 141
(2012/02/03)
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- Co-ordination chemistry of 3S-aminopyrrolidine and 3S-(methyl-amino)pyrrolidine: Crystallisation of the two diastereomers of dichloro[3S-(R,S-methylamino)pyrrolidine]palladium(II)
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Complexes of divalent Cu, Ni, Pd and Pt with 3S-aminopyrrolidine (S-ap) have been prepared and characterised by a combination of NMR, CD, electronic, IR and microanalytical techniques. The chosen chirality of the stereogenic carbon (S) forces the secondary nitrogen to adopt the R stereochemistry on co-ordination with the conformation of the 5-membered chelate being λ. The planar [M(S-ap)2]2+ complexes exist as a mixture of cis and trans isomers in the solid state and in solution. The trans arrangement is forced upon co-ordination of an axial donor (X = halide, thiocyanate or nitrite) in the five-co-ordinate ions [Cu(S-ap)2X]+. Methylation of the primary amine of S-ap generates another secondary nitrogen centre in the new ligand 3S-(methylamino)pyrrolidine, S-meap. This exocyclic nitrogen is not restricted to a single configuration on co-ordination. The complexes [M(S-meap)Cl2], where M = Pd or Pt, have been prepared and characterised. Both diastereoisomers (R- and S-NMe) of [Pd(S-meap)Cl2] crystallise from aqueous solution as distinct crystal forms which can be separated by mechanical means. The structure of the NMe(R) isomer has been determined by X-ray crystallography.
- Newman, Paul D.,Hursthouse, Michael B.,Malik, K. M. Abdul
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p. 599 - 606
(2007/10/03)
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- Regioselective reductions of various 3-aminosuccinimides; application to the synthesis of two heterocyclic systems
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The synthesis of novel pyrrolo[3,2-c]isoquinolines is investigated starting from 3-aminosuccinimides. Various known routes leading to 3-aminosuccinimides were tested but a new approach via nucleophilic addition of arylalkylamines on maleimide gave better results. The regioselectivity of the reduction of these compounds was shown to depend on the degree of substitution of the concerned 3-aminosuccinimide. The hydroxylactams are formed in-situ, then converted into the ethoxylactams. The latter, after generation of an iminium salt, afforded the target pyrroloisoquinolines and two further derivatives of another new heterocyclic system: the 3,6-methano-2,5-benzodiazocine.
- Briere, Jean-Francois,Charpentier, Patricia,Dupas, Georges,Queguiner, Guy,Bourguignon, Jean
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p. 2075 - 2086
(2007/10/03)
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- Handy access to chiral N,N'-disubstituted 3-aminopyrrolidines
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A new and rapid synthesis of (S)-3-aminopyrrolidines Z is proposed from N-protected (S)-Asparagine. Basic cyclization of methyl N-Z-(S)-Asparaginate 1 followed by one-pot N-benzylation directly leads to (S)-aminosuccinimide 3 which, after cleavage of the
- Maddaluno,Corruble,Leroux,Ple,Duhamel
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p. 1239 - 1242
(2007/10/02)
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- Cyclo-(L-asparagyl-L-asparagyl) : Preparation and Crystal Structure
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Two methods are described for the preparation of optically pure cyclo-(L-asparagyl-L-asparagyl) : (i) by self-condensation of (S)-3-aminopyrrolidine-2,5-dione in refluxing acetonitrile, and (ii) by self-co
- Howes, Colin,Alcock, Nathaniel W.,Golding, Bernard T.,McCabe, Richard W.
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p. 2287 - 2291
(2007/10/02)
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