- Sequential ruthenium catalysis for olefin isomerization and oxidation: Application to the synthesis of unusual amino acids
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How can you use a ruthenium isomerization catalyst twice? A ruthenium-catalyzed sequence for the formal two-carbon scission of allyl groups to carboxylic acids has been developed. The reaction includes an initial isomerization step using commercially available ruthenium catalysts followed by in situ transformation of the complex to a metal-oxo species, which is capable of catalyzing subsequent oxidation reactions. The method enables enantioselective syntheses of challenging α-tri- and tetrasubstituted α-amino acids including an expedient total synthesis of the antiepileptic drug levetiracetam.
- Liniger, Marc,Liu, Yiyang,Stoltz, Brian M.
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supporting information
p. 13944 - 13949
(2017/11/06)
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- Asymmetric Synthesis of α-Alkyl-α-amino Acids from Chromium-Carbene-Complex-Derived β-Lactams
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Optically active bicyclic β-lactam 3 was synthesized by photolysis of optically active oxazolidine carbene chromium complex 1 with oxazine 2.Conversion of the oxazolidine to the oxazolidinone gave a bicyclic β-lactam readily α-alkylated.Cleavage of the alkylated β-lactam gave optically active ester aldehyde 7, which was converted to a number of optically active α-alkyl-α-amino acids.These include (R)-α-methylserine, (S)-α-methylglutamic acid, (S)-α-methylornithine, (S)-vinylalanine, (S)-ethynylalanine, and (S)-2-methyl-2,3-diaminopropionic acid.
- Colson, Pierre-Jean,Hegedus, Louis S.
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p. 5918 - 5924
(2007/10/02)
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