- The synthesis of trans-perhydroindolic acids and their application in asymmetric domino reactions of aldehyde esters with β,γ-unsaturated α-keto esters
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(2S,3aR,7aS)-Perhydroindolic acid, the key intermediate in the synthesis of trandolapril, and its trans-isomers, were readily prepared. These proline-like molecules are unique in that they contain a rigid bicyclic structure, with two hydrogen atoms trans to each other at the bridgehead carbon atoms. These molecules were used successfully as chiral organocatalysts in asymmetric domino Michael addition/cyclization reactions of aldehyde esters with β,γ-unsaturated α-keto esters. They proved to have excellent catalytic behavior, allowing for the synthesis of multi-substituted, enantiomerically enriched hemiacetal esters. Under optimal conditions (using 10 mol% catalyst loading), a series of β,γ-unsaturated α-keto esters was examined with up to 99% de, ee and yield, respectively. Additionally, the enantiomerically enriched hemiacetal esters could be readily transformed into their corresponding bioactive pyrano[2,3-b]pyrans (possessing a multi-substituted bicyclic backbone). Copyright
- Shen, Jiefeng,Liu, Delong,An, Qianjin,Liu, Yangang,Zhang, Wanbin
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- PROCESS FOR THE SYNTHESIS OF AN ACE INHIBITOR
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A process for the synthesis of trandolapril which comprises condensing N-[I-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanine N-carboxyanhydride with trans octahydro-1H- indole-2-carboxylic acid in a first organic solvent comprising a water immiscible inert organic solvent and in the presence of a base, and isolating trandolapril from a second organic solvent. N-[1-(S)-ethoxycarbonyl-3-phenylpropyl]-L-alanine N-carboxyanhydride may also be condensed with (2S,3aR,7aS) octahydro-1H-indole-2-carboxyIic acid in a first organic solvent and in the presence of a base, and trandolapril isolated. There is also provided a process for the resolution of racemic trans octahydro-1H-indole-2-carboxylc acid.
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Page/Page column 14
(2008/06/13)
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- Efficient access to N-protected derivatives of (R,R,R)- and (S,S,S)-octahydroindole-2-carboxylic acid by HPLC resolution
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The preparation of the proline analogue (2S,3aS,7aS)-octahydroindole-2-carboxylic acid (Oic) and its enantiomer, (2R,3aR,7aR)-Oic, is described. A racemic precursor has been synthesized in good yield and subjected to HPLC resolution on a chiral column. The high efficiency of both the synthetic and chromatographic procedures has allowed the isolation of multigram quantities of each amino acid in enantiomerically pure form and suitably protected for use in peptide synthesis.
- Sayago, Francisco J.,Jimenez, Ana I.,Cativiela, Carlos
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p. 2358 - 2364
(2008/02/12)
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- Process for the preparation of intermediates of trandolapril and use thereof for the preparation of trandolapril
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A process for the preparation of an intermediate of trandolapril, (2S,3aR,7aS)-perhydroindole-2-carboxylic acid of Formula II is provided. Also provided are processes for preparing trandolapril.
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Page/Page column 5-6
(2010/10/20)
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- DIASTEREOSELECTIVE SYNTHESIS OF BICYCLIC AMINO ACIDS VIA RING CONTRACTION OF α-CHLOROLACTAMS
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Bicyclic lactams were converted to their α-chloro-derivatives and subjected to ring contraction under basic conditions to give bicyclic acids in diasteroselective fashion.
- Henning, R.,Urbach, H.
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p. 5339 - 5342
(2007/10/02)
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- COUPLING OF β-ACETAMIDO RADICALS WITH α-CHLORO ACRYLONITRILE - A NEW ACCESS TO DISUBSTITUTED PROLINE DERIVATIVES
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β-Acetamido radicals are prepared by reduction of organomercurials and coupled with α-chloro-acrylonitrile.The coupling products are further converted to proline derivatives.
- Henning, R.,Urbach, H.
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p. 5343 - 5346
(2007/10/02)
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