- The kinetic resolution of oxazinones by alcoholysis: access to orthogonally protected β-amino acids
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The catalytic, alcoholytic kinetic resolution of oxazinones is reported. A novel, stereochemically dense cinchona alkaloid-based catalyst can facilitate the highly enantiodiscriminatory (Sup to 101) ring-opening of oxazinones equipped with electrophilic aryl units to generate orthogonally protected β-amino acids for the first time.
- Cronin, Sarah A.,Connon, Stephen J.
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supporting information
p. 7348 - 7352
(2021/09/07)
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- Iridium-catalysed C-H borylation of β-aryl-aminopropionic acids
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Iridium-catalysed catalytic, regioselective C-H borylation of β-aryl-aminopropionic acid derivatives gives access to 3,5-functionalised protected β-aryl-aminopropionic acid boronates. The synthetic versatility of these new boronates is demonstrated through sequential one-pot functionalisation reactions to give diverse building blocks for medicinal chemistry. The C-H borylation is also effective for dipeptide substrates. We have exemplified this methodology in the synthesis of a pan αv integrin antagonist.
- MacDonald, Simon J. F.,Nortcliffe, Andrew,Robinson, Henry,Simelis, Klemensas,Stillibrand, Joe
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supporting information
p. 6696 - 6701
(2020/09/21)
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- Carica papaya lipase catalysed resolution of β-amino esters for the highly enantioselective synthesis of (S)-dapoxetine
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An efficient synthesis of the (S)-3-amino-3-phenylpropanoic acid enantiomer has been achieved by Carica papaya lipase (CPL) catalysed enantioselective alcoholysis of the corresponding racemic N-protected 2,2,2-trifluoroethyl esters in an organic solvent. A high enantioselectivity (E > 200) was achieved by two strategies that involved engineering of the substrates and optimization of the reaction conditions. Based on the resolution of a series of amino acids, it was found that the structure of the substrate has a profound effect on the CPL-catalysed resolution. The enantioselectivity and reaction rate were significantly enhanced by switching the conventional methyl ester to an activated trifluoroethyl ester. When considering steric effects, the substituted phenyl and amino groups should not both be large for the CPL-catalysed resolution. The mechanism of the CPL-catalysed enantioselective alcoholoysis of the amino acids is discussed to delineate the substrate requirements for CPL-catalysed resolution. Finally, the reaction was scaled up, and the products were separated and obtained in good yields (≥ 80 %). The (S)-3-amino-3- phenylpropanoic acid obtained was used as a key chiral intermediate in the synthesis of (S)-dapoxetine with very high enantiomeric excess (> 99 %). A carica papaya lipase catalysed resolution of N-protected β-phenylalanine esters has been developed. High enantioselectivity was achieved by two strategies that involved engineering of the substrates and optimization of the reaction conditions. After 50 % conversion, the products were separated and used as key chiral intermediates for the synthesis of (S)-dapoxetine with > 99 % ee. Copyright
- You, Pengyong,Qiu, Jian,Su, Erzheng,Wei, Dongzhi
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p. 557 - 565
(2013/03/13)
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- β-phenylalanine derivatives as integrin antagonists
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The present invention relates to compounds of the general formula (1) wherein R4 is —SO2R4, —COOR4′, —COR4′, —CONR4′2 or —CSNR4′2; R4′is hydrogen, a substituted or unsubstituted alkyl or cycloalkyl residue, a substituted or unsubstituted aryl residue or a saturated or unsaturated, optionally substituted heterocyclic residue; R4″is a substituted or unsubstituted alkyl or cycloalkyl residue, a substituted or unsubstituted aryl residue or a saturated or unsaturated, optionally substituted heterocyclic residue; L is a sulphonamide, amide, ether, ester, keto, urea, thioether, sulphoxide or sulphone unit optionally extended by one or two methylene groups; and X is N, O or S; and their physiologically acceptable salts and stereoisomers. The present invention furthermore relates to a process for the preparation of the compounds of the formula (1), a pharmaceutical composition containing at least one of these compounds, and the use of compounds of the formula (1) for the production of a pharmaceutical composition having integrin-antagonistic action and in particular for the therapy and prophylaxis of cancer, osteolytic diseases such as osteoporosis, arteriosclerosis, restenosis and ophthalmic disorders.
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- One-Pot Cyclization of Alkoxy-3-Aminoindan-1-ones.
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3-Amino-3-alkoxyphenylpropionic acids, prepared from alkoxybenzaldehydes, are cyclized in one step into 3-aminoindan-1-ones using trifluoroacetic acid and trifluoroacetic anhydride. Key Words: One-pot cyclization; Aminoindanones; Electrodonating substitue
- Dallemagne, Patrick,Rault, Sylvain,Pilo, Juan Carlos,Foloppe, Marie Paule,Robba, Max
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p. 6327 - 6328
(2007/10/02)
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