- MODIFIED PHOTOBEHAVIOR OF CARBOXYLIC ACID DERIVATIVES INDUCED BY PROTONATION
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A series of carboxylic acid derivatives 1-6 containing a second interacting function have been converted into the corresponding O-protonated species or acylium ions upon treatment with 96percent sulfuric acid or oleum, respectively, at room temperature.The resulting stable cations have been spectroscopically characterized and submitted to irradiation.Cis-trans photoisomerization was observed in the ionic species derived from trans-crotonic, fumaric and maleic acids, and maleic anhydride.By contrast protonated crotonolactone 5a was found to be photostable.Finally, protonated α-bromobutyrolactone 6a was clean and efficiently dehydrohalogenated to 5a upon irradiation.Since the normal n ?* photoreactions of the uncharged carboxylic acid and their derivatives are inhibited under these conditions, protonation can be envisaged as a chemical selective method for photoprotection of the carboxy group.
- Amat, Ana M.,Asensio, Gregorio,Castello, Maria J.,Miranda, Miguel A.,Simon-Fuentes, Antonio
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- INHIBITORS OF BRUTON'S TYROSINE KINASE AND METHODS OF THEIR USE
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Compounds of formula (I') and methods of their use and preparation, as well as compositions comprising compounds of formula (I').
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Page/Page column 150
(2018/06/30)
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- INHIBITORS OF BRUTON'S TYROSINE KINASE AND METHODS OF THEIR USE
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The present disclosure is directed to compounds of formula I and methods of their use and preparation, as well as compositions comprising compounds of formula I.
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Page/Page column 150
(2017/09/02)
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- PROCESS FOR THE PRODUCTION OF CARNITINE BY CYCLOADDITION
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The invention relates to a method for the production of L-carnitine, wherein a chiral β-lactone carnitine precursor is obtained by a [2+2] cycloaddition of ketene with an aldehyde X—CH2—CHO, wherein X is selected from Cl, Br, I and trimethylamine, in the presence of a chiral catalyst.
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Page/Page column 10
(2012/02/03)
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- Analogues of γ-hydroxybutyric acid. Synthesis and binding studies
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Substituted 4-hydroxybutyric (GHB) or trans-4-hydroxycrotonic acids (T-HCA) and structurally related compounds were synthesized and submitted to [3H]GHB binding. Structure-activity relationship studies highlighted for [3H]GHB binding (a) the necessity of a nonlactonic, relatively extended conformation of the γ-hydroxybutyric chain, (b) the existence of some bulk tolerance in the vicinity of the hydroxyl group, and (c) the high sensitivity toward isosteric replacement of the carboxyl or the hydroxyl groups. T-HCA has been recently identified as a naturally occurring substance in the central nervous system (CNS) and shows a better affinity than GHB. Our findings are in favor of the presence in the CNS of specific GHB binding sites, which are different from the GABA and the picrotoxin binding sites, and for which T-HCA may be an endogenous ligand.
- Bourguignon,Schoenfelder,Schmitt,Wermuth,Hechler,Charlier,Maitre
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p. 893 - 897
(2007/10/02)
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