- Hydrogen-Borrowing Alkylation of 1,2-Amino Alcohols in the Synthesis of Enantioenriched γ-Aminobutyric Acids
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For the first time we have been able to employ enantiopure 1,2-amino alcohols derived from abundant amino acids in C?C bond-forming hydrogen-borrowing alkylation reactions. These reactions are facilitated by the use of the aryl ketone Ph*COMe. Racemisation of the amine stereocentre during alkylation can be prevented by the use of sub-stoichiometric base and protection of the nitrogen with a sterically hindered triphenylmethane (trityl) or benzyl group. The Ph* and trityl groups are readily cleaved in one pot to give γ-aminobutyric acid (GABA) products as their HCl salts without further purification. Both steps may be performed in sequence without isolation of the hydrogen-borrowing intermediate, removing the need for column chromatography.
- Hall, Christopher J. J.,Goundry, William R. F.,Donohoe, Timothy J.
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supporting information
p. 6981 - 6985
(2021/03/01)
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- POLYMYXIN ANALOGS USEFUL AS ANTIBIOTIC POTENTIATORS
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The disclosure provides compounds of the formula (I) or a tautomer thereof, or a pharmaceutically acceptable salt of either of the foregoing. The variables A, R1, and R2 are defined in the disclosure. The disclosure further includes pharmaceutical compositions comprising a compound of formula I together with at least one pharmaceutically acceptable carrier. The disclosure also includes a method of sensitizing bacteria to an antibacterial agent, comprising administering to a patient infected with the bacteria, simultaneously or sequentially, a therapeutically effective amount of the antibacterial agent and a compound of formula (I).
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Paragraph 0231
(2017/12/09)
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- Preparation of the optically pure N-methyl amino ester method and product
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The invention belongs to the field of organic synthesis of amino acids and discloses a method for preparing optically pure N-methyl amino-acid ester. The method comprises the following steps of carrying out esterification reaction on amino acid as a starting raw material and aldehyde to form an imine intermediate, carrying out reductive amination in the presence of palladium carbon, and carrying out hydrogenation and debenzylation to finally synthesize optically pure N-methyl amino-acid ester. The method has the advantages of simplicity in method, mild reaction conditions and good adaptability and side chains of D-type or L-type amino acid do not need to be protected.
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Paragraph 0053-0054
(2017/04/13)
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- Facile synthesis of β-amino disulfides, cystines, and their direct incorporation into peptides
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Herein, we report a simple and efficient methodology for the synthesis of β-amino disulfides by regioselective ring opening of sulfamidates with benzyltriethylammonium tetrathiomolybdate [BnNEt3] 2MoS4. Stability and reactivity of different protecting groups under the reaction conditions have been discussed. This methodology has also been extended to serine and threonine derived sulfamidates to furnish cystine and 3,3′-dimethyl cystine derivatives. Georg Thieme Verlag.
- Nasir Baig,Kanimozhi, Catherine K.,Sudhir, V. Sai,Chandrasekaran, Srinivasan
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scheme or table
p. 1227 - 1232
(2009/09/06)
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- Facile synthesis of highly functionalized N-methyl amino acid esters without side-chain protection
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(Chemical Equation Presented) The facile, two-pot synthesis of N-methyl amino acid esters by way of reductive amination is presented. Side chain protection schemes are not required, the starting materials are all commercially available, and the synthetic
- White, Kimberly N.,Konopelski, Joseph P.
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p. 4111 - 4112
(2007/10/03)
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- Preparation and Use of Aziridino Alcohols as Promoters for the Enantioselective Addition of Dialkylzinc Reagents to N-(Diphenylphosphinoyl) Imines
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A set of chiral aziridino alcohols 2-5 has been synthesized starting from either readily available amino acids (L-serine, L-threonine, and allo-L-threonine) or simple olefins (using Sharpless asymmetric aminohydroxylation and dihydroxylation reactions). Chiral ligands 2-5 have been tested as promoters for the enantioselective addition of dialkylzinc reagents to N-(diphenylphosphinoyl) imines 1. The influence of the substituants on the aziridine ring and the alcohol moiety on the selectivity has been studied, and in the best case, an enantiomeric excess of up to 94% could be obtained. Acidic hydrolysis of the initially formed N-protected amines 6 led to the corresponding free amines 7 without racemization. Although a stoichiometric amount of the ligand was used, about 90% of it could be recovered during the workup and reused without significant loss of chiral induction. The utility of the aziridino alcohols 2-5 as catalysts for the same reaction has also been evaluated and enantiomeric excesses of up to 76% were achieved using 0.25 equiv of the chiral ligand. A possible transition state for the addition reaction is also proposed.
- Andersson, Pher G.,Guijarro, David,Tanner, David
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p. 7364 - 7375
(2007/10/03)
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- N-methyl threonine analogues of deglycobleomycin A2: Synthesis and evaluation
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The synthesis of 5 and its D-allo-threonine epimer 6 and the comparison of their DNA cleavage efficiency and selectivity with that of deglycobleomycin A2 (3) are detailed. The studies illustrate that N-methylation of the L-threonine subunit wit
- Boger, Dale L.,Teramoto, Shuji,Cai, Hui
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p. 1577 - 1589
(2007/10/03)
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