- Recyclable Ligands for the Non-Enzymatic Dynamic Kinetic Resolution of Challenging α-Amino Acids
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Structurally simple and inexpensive chiral tridentate ligands were employed for substantially advancing the purely chemical dynamic kinetic resolution (DKR) of unprotected racemic tailor-made α-amino acids (TM-α-AAs), enabling the first DKR of TM-α-AAs bearing tertiary alkyl chains as well as multiple unprotected functional groups. Owing to the operationally convenient conditions, virtually complete stereoselectivity, and full recyclability of the source of chirality, this method should find wide applications for the preparation of TM-α-AAs, especially on large scale. The non-enzymatic dynamic kinetic resolution of racemic α-amino acids bearing tertiary alkyl chains and multiple unprotected functional groups is based on the enantioselective formation of nickel(II) complexes and their hydrolysis under convenient conditions. The specially designed chiral ligands are inexpensive and can be quantitatively recycled.
- Nian, Yong,Wang, Jiang,Zhou, Shengbin,Wang, Shuni,Moriwaki, Hiroki,Kawashima, Aki,Soloshonok, Vadim A.,Liu, Hong
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supporting information
p. 12918 - 12922
(2015/11/02)
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- A process for the preparation of enantiomerically pure tert-leucine
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A Process for the Preparation of Enantiomerically Pure tert-Leucine : Enantiomerically pure L-tert-leucine and D-tert-leucine were prepared from (DL)-tert-leucine by diastereomeric salt formation using dibenzoyl-d-tartaric acid as the resolving agent.
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Page/Page column 4
(2012/10/18)
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- PROCESS FOR THE PREPARATION OF ENANTIOMERICALLY PURE tert-LEUCINE
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Enantiomerically pure L-tert-leucine and D-tert-leucine were prepared from (DL)-tert-leucine by diastereomeric salt formation using dibenzoyl-d-tartaric acid as the resolving agent.
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- Azapeptide derivatives as HIV protease inhibitors
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This invention relates to novel compounds of the Formula Ib: that are azapeptides, and pharmaceutically acceptable salts thereof. More specifically, the invention relates to novel azapeptide compounds that are derivatives of the HIV protease inhibitor atazanavir sulfate. This invention also provides pyrogen-free compositions comprising one or more compounds of the invention and a carrier, and the use of the disclosed compounds and compositions in methods of treating diseases and conditions that are treated by administering HIV protease inhibitors. The invention also relates to the use of one or more of the disclosed compounds as reagents in analytical studies involving atazanavir.
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Page/Page column 40
(2009/01/24)
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- Catalytic asymmetric acylcyanation of imines
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(Chemical Equation Presented) The less problematic acetyl cyanide can be used instead of toxic HCN for the highly enantioselective acyl-Strecker-type reaction. In the presence of an N-benzylimine and a catalytic amount of Jacobsen's catalyst 1, the desire
- Pan, Subhas Chandra,Zhou, Jian,List, Benjamin
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p. 612 - 614
(2008/02/01)
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- Oxidative rearrangement of 2-substituted oxazolines. A novel entry to 5,6-dihydro-2H-1,4-oxazin-2-ones and morpholin-2-ones
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A novel synthesis of 5,6-dihydro-2H-1,4-oxazin-2-ones by SeO2-promoted oxidative rearrangement of 2-alkyl- and 2-(arylmethyl)oxazolines is described. Yields are good to excellent (up to 94%) with the highest yields obtained for 2-arylmethyl- and 2-neopentyl-substituted oxazolines. This reaction provides convenient access to novel 5-aryl-substituted dihydrooxazinones in high yield. The latter compounds are important 'chiral glycine' synthons for asymmetric synthesis of α-amino acids. Since oxazolines are readily derived from carboxylic acids or their equivalents, this oxidative rearrangement constitutes an entry to synthesis of α-amino acids from carboxylic acids. A mechanism is proposed to account for the rearrangement involving a 'nitrilium to acylium' 1,2-migration.
- Shafer,Molinski
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p. 2044 - 2050
(2007/10/03)
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