- Solventless mechanosynthesis of N-protected amino esters
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Mechanochemical derivatizations of N- or C-protected amino acids were performed in a ball mill under solvent-free conditions. A vibrational ball mill was used for the preparation of N-protected α- and β-amino esters starting from the corresponding N-unmasked precursors via a carbamoylation reaction in the presence of di-tert-butyl dicarbonate (Boc2O), benzyl chloroformate (Z-Cl) or 9-fluorenylmethoxycarbonyl chloroformate (Fmoc-Cl). A planetary ball mill proved to be more suitable for the synthesis of amino esters from N-protected amino acids via a one-pot activation/esterification reaction in the presence of various dialkyl dicarbonates or chloroformates. The spot-to-spot reactions were straightforward, leading to the final products in reduced reaction times with improved yields and simplified work-up procedures.
- Konnert, Laure,Lamaty, Frederic,Martinez, Jean,Colacino, Evelina
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p. 4008 - 4017
(2014/05/20)
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- NOVEL PRECURSORS OF GLUTAMATE DERIVATIVES
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This invention relates to novel precursors suitable for 18F radiolabeling of glutamate derivatives, methods for preparing such compounds and its intermediates, compositions comprising such compounds, kits comprising such compounds or compositio
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Page/Page column 38
(2012/11/14)
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- Novel precursors of glutamate derivatives
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This invention relates to novel precursors suitable for 18F radiolabeling of glutamate derivatives, methods for preparing such compounds and its intermediates, compositions comprising such compounds, kits comprising such compounds or compositions and methods for 18F radiolabeling of glutamate derivatives wherein the obtained 18F radiolabeled glutamate derivatives are suitable for diagnostic imaging by Positron Emission Tomography (PET) of proliferative diseases e.g. tumor in mammals.
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Page/Page column 23
(2012/12/13)
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- New Methods and Reagents in Organic Synthesis. 67. A General Synthesis of Derivatives of Optically Pure 2-(1-Aminoalkyl)thiazole-4-carboxylic Acids
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Preparations of 2-(1-aminoalkyl)thiazole-4-carboxylic acids (thiazole amino acids), important constituents of a series of cytotoxic cyclic peptides from marine organisms, have been conveniently and efficiently achieved as their N- and C-protected derivatives 6 from N-Boc or N-Z α-amino acids 1 in five steps.Esterification of 1 with methyl iodide followed by reduction with lithium chloride-sodium borohydride afforded N-protected amino alcohols 3.Selective reduction of the α-ester functions of the glutamic acid derivatives (Z-D- and Z-L-Glu(O-t-Bu)-OMe and O-t-Bu) was also achieved under the above reduction conditions.Dimethyl sulfoxide oxidation, followed by condensation with cysteine methyl ester afforded the thiazolidine derivatives 5, which were conveniently dehydrogenated with manganese dioxide, called chemical manganese dioxide (CMD) and produced for batteries, to give the desired thiazole amino acid derivetives 6.The glutamine derivatives (Z-D- and Z-L-(gln)Thz-OMe) were prepared from the corresponding glutamic acid derivatives (Z-D- and Z-L-6f).No appreciable racemization was observed in the above conversion, which was proven by HPLC of the 3,5-dinitrobenzoyl derivatives of thiazole amino acids 6 using a chiral column.
- Hamada, Yasumasa,Shibata, Makoto,Sugiura, Tsuneyuki,Kato, Shinji,Shioiri, Takayuki
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p. 1252 - 1255
(2007/10/02)
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