- Nucleophilic ring-opening of epoxide and aziridine acetates for the stereodivergent synthesis of β-Hydroxy and β-Amino γ-Lactams
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A highly regio- and stereoselective synthesis of novel β,γ- disubstituted γ-lactams with either an anti or syn relative configuration was developed from readily available epoxide and aziridine acetates. The key steps include the regio- and diastereocontrolled nucleophilic ring-opening of these three-membered heterocycles followed by mild reductive cyclization of the γ-azido ester intermediate. The method was also extended to an asymmetric synthesis of (4R,5S)-4-hydroxy-5-phenylpyrrolidin-2-one from a chiral epoxide acetate. The main features of this versatile synthesis of functionalized γ-lactams include the involvement of inexpensive reagents and mild conditions together with high chemical efficiency.
- Bisol, Tula B.,Bortoluzzi, Adailton J.,Sa, Marcus M.
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experimental part
p. 948 - 962
(2011/04/12)
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- PROCESS FOR STRAIGHTENING KERATIN FIBRES WITH A HEATING MEANS AND DENATURING AGENTS
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The invention relates to a process for straightening keratin fibres, comprising: (i) a step in which a straightening composition containing at least two denaturing agents is applied to the keratin fibres, (ii) a step in which the temperature of the keratin fibres is raised, using a heating means, to a temperature of between 110 and 250° C.
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- Simple and efficient cleavage of the N-(1-phenylethyl) unit of carboxamides with methanesulfonic acid
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Cleavage of the N-(1-phenylethyl) unit of carboxamides using less than 1 equiv of MsOH in refluxing toluene was found to be simple and very efficient leading to the desired amides in good to excellent yields, and also proved to be more effective compared with reductive methods using hydrogen sources, or acid hydrolysis reagents such as TFA and TsOH. The method selectively cleaved only the N-(1-phenylethyl) group of N-benzyl-N-(1-phenylethyl)amides.
- Paik, Seunguk,Lee, Jun Young
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p. 1813 - 1815
(2007/10/03)
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- An efficient scalable process for the synthesis of N-Boc-2-tert-butyldimethylsiloxypyrrole
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A safe, reliable and scalable process for the preparation of N-Boc-2-tert-butyldimethylsiloxy-pyrrole (TBSOP) is described. In a three-step, one-pot sequence (±)-4-amino-3-hydroxybutyric acid was converted to N-Boc-4-hydroxy-2-pyrrolidinone. This stable crystalline product was isolated by filtration directly from the reaction mixture. Dehydration followed by enolization and silylation produced the target compound without the need for chromatographic purification. The process was demonstrated in the pilot plant to make multikilogram quantities of material in 85% overall yield.
- Tian, Zhenping,Rasmussen, Michael,Wittenberger, Steven J.
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p. 416 - 418
(2013/09/06)
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- Process for producing optically active alcohol
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A novel process in which an optically active alcohol compound having a desired absolute configuration and a high optical purity can be obtained by asymmetrically hydrogenating a β-keto acid compound through a simple operation. An optically active alcohol represented by the following general formula (III) : (wherein R1 represents a C1-C15 alkyl group which may have one or more substituents (selected from halogen atoms, a hydroxyl group, an amino group, amino groups protected by a protective group, amino groups protected by a mineral acid or organic acid, amino groups substituted with one or more C1-C4 lower alkyl groups, a benzyloxy group, C1-C4 lower alkoxy groups, C1-C4 lower alkoxycarbonyl groups, and aryl groups) or an aryl group; and R2 represents a C1-C8 lower alkyl group, or a benzyl group which may have one or more substituents) is obtained by asymmetrically hydrogenating a β-keto ester compound represented by the following general formula (I): (wherein R1 and R2 are the same as defined above) in the presence of at least one ruthenium complex having as a ligand an optically active tertiary diphosphine compound represented by the following general formula (II): (wherein R3 and R4 each independently represent a cycloalkyl group, an unsubstituted or substituted phenyl group, or a five-membered heteroaromatic ring residue).
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- Process for preparing 4-hydroxy-2-pyrrolidone
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A improved process for preparing 4-hydroxy-2-pyrrolidone of the formula STR1 which is characterized in reacting a 4-halogeno-3-hydroxybutyrate and an alkali metal or alkaline earth metal azide, to produce a 4-azido-3-hydroxybutyrate and hydrogenating an azide group of the ester compound and then cyclizing a hydrogenated compound. 4-Hydroxy-2-pyrrolidone is useful for an intermediate of medicines and agricultural chemicals.
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- Structure elucidation of pantherine, a flycidal alkaloid from Amanita pantherina (DC.) FR.
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Pantherine is identified as 5-aminomethyl-3-hydroxyisoxazole by means of spectroscopic experiments and chemical correlation with synthetic compounds.
- Konda,Takahashi,Onda
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p. 1083 - 1087
(2007/10/02)
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- FACILE SYNTHESIS OF γ-, δ-, AND ε-LACTAMS BY CYCLODEHYDRATION OF ο-AMINO ACIDS ON ALUMINA OR SILICA GEL
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It has been found that γ-, δ-, and ε-amino acids cyclodehydrate easily to their corresponding lactams by the action of alumina or silica gel in boiling toluene.
- Blade-Font, Artur
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p. 2443 - 2446
(2007/10/02)
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