- A Scalable, Combined-Batch, and Continuous-Flow Synthesis of a Bio-Inspired UV-B Absorber
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A new, chromatography-free synthesis for the preparation of an experimental UV-B absorber is reported. A key step of the process is a one-pot partial reduction of a symmetrical imide with a sequential dehydration step. The synthesis uses several continuous-flow steps to increase sample throughput and was used to prepare sufficient material to support further testing activities in >99 % purity.
- York, Mark,Jarvis, Karen E.,Freemont, Jamie A.,Ryan, John H.,Savage, G. Paul,Logan, Stephanie A.,Bright, Larissa
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- Synthesis of Cyclic Anhydrides via Ligand-Enabled C–H Carbonylation of Simple Aliphatic Acids
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The development of C(sp3)–H functionalizations of free carboxylic acids has provided a wide range of versatile C?C and C?Y (Y=heteroatom) bond-forming reactions. Additionally, C–H functionalizations have lent themselves to the one-step preparation of a number of valuable synthetic motifs that are often difficult to prepare through conventional methods. Herein, we report a β- or γ-C(sp3)–H carbonylation of free carboxylic acids using Mo(CO)6 as a convenient solid CO source and enabled by a bidentate ligand, leading to convenient syntheses of cyclic anhydrides. Among these, the succinic anhydride products are versatile stepping stones for the mono-selective introduction of various functional groups at the β position of the parent acids by decarboxylative functionalizations, thus providing a divergent strategy to synthesize a myriad of carboxylic acids inaccessible by previous β-C–H activation reactions. The enantioselective carbonylation of free cyclopropanecarboxylic acids has also been achieved using a chiral bidentate thioether ligand.
- Herron, Alastair N.,Yu, Jin-Quan,Zhuang, Zhe
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supporting information
p. 16382 - 16387
(2021/06/23)
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- Efficient cyclodehydration of dicarboxylic acids with oxalyl chloride
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Literature examples illustrating the use of oxalyl chloride to prepare dicarboxylic acid anhydrides are surprisingly limited. At the same time, we have discovered a method involving the use of this readily available reagent which allowed the preparation of novel cyclic anhydrides where other, more conventional, methods had failed. Herein, we demonstrate that the method is applicable to a wide diversity of substrates, delivers good to excellent yields of cyclic anhydrides without chromatographic purification and can be considered a synthetic tool of choice whenever dicarboxylic acid cyclodehydration is required.
- Kantin, Grigory,Chupakhin, Evgeny,Dar'in, Dmitry,Krasavin, Mikhail
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supporting information
p. 3160 - 3163
(2017/07/18)
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- UV ABSORBING COMPOUNDS, COMPOSITIONS COMPRISING SAME AND USES THEREOF
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There is provided a range of novel compounds which have been demonstrated to have useful UV absorbing properties. These compounds will find use in a range of applications such as active components in sunscreen formulations, paints, plastics, fabrics, glass and UV protective coatings.
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Paragraph 0036
(2015/02/02)
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- SYNTHESIS OF UV ABSORBING COMPOUNDS
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A method of synthesis is provided to obtain a range of UV absorbing compounds. The method broadly involves(a) the reduction of a glutarimide or its reaction with a carbon nucleophile; (b) when step (a) is a reduction, exposing the product of step (a) to an acidic environment to form a cyclic amide; (c) reducing the product of step (a) or step (b) to form a corresponding enamine; and subjecting the enamine product of step (c) to an acylation.
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Paragraph 00127; 00128
(2014/06/23)
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- The development of a new class of inhibitors for betaine-homocysteine S-methyltransferase
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Betaine-homocysteine S-methyltransferase (BHMT) is an important zinc-dependent methyltransferase that uses betaine as the methyl donor for the remethylation of homocysteine to form methionine. In the liver, BHMT performs to half of the homocysteine remethylation. In this study, we systematically investigated the tolerance of the enzyme for modifications at the "homocysteine" part of the previously reported potent inhibitor (R,S)-5-(3-amino-3-carboxy-propylsulfanyl)-pentanoic acid (1). In the new compounds, which are S-alkylated homocysteine derivatives, we replaced the carboxylic group in the "homocysteine" part of inhibitor 1 with different isosteric moieties (tetrazole and oxadiazolone); we suppressed the carboxylic negative charge by amidations; we enhanced acidity by replacing the carboxylate with phosphonic or phosphinic acids; and we introduced pyrrolidine steric constraints. Some of these compounds display high affinity toward human BHMT and may be useful for further pharmacological studies of this enzyme. Although none of the new compounds were more potent inhibitors than the reference inhibitor 1, this study helped to completely defi ne the structural requirements of the active site of BHMT and revealed the remarkable selectivity of the enzyme for homocysteine.
- Pi?ha, Jan,Vaňek, Václav,Budě??sińsky, Milo?,Mlad?ková, Jana,Garrow, Timothy A.,Ji??acek, Ji??i
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p. 256 - 275
(2013/10/01)
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- Microwave-assisted selective protection of glutaraldehyde and its symmetrical derivatives as monoacetals and -thioacetals
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Six monoprotected acetals and -thioacetals of glutaradehyde and its symmetrical dimethyl derivatives were synthesized. Microwave-assisted heating proved to be a substantially more selective method for monoprotection than conventional heating. All reactions were efficient and only traces of diprotected material were formed.
- Flink, Heli,Putkonen, Tiina,Sipos, Attila,Jokela, Reija
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experimental part
p. 887 - 890
(2010/03/24)
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- Two-Step Redox Systems, XXX. - Spectroscopic and Electrochemical Properties of N-substituted 1,4-Dihydro-4,4-dimethylpyridines
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The exceptional behaviour of the N-substituents R=CO2C2H5 and especially R=CN in the redox system 1 is examined by the partly new 1,4-dihydropyridines 2 which serve as models for 1RED.Since no anomalies are observed in 2 the specific effects in 1 are probably due to the higher oxidation levels of 1.
- Hesse, Konrad,Huenig, Siegfried,Wenner, Hermann
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p. 2079 - 2086
(2007/10/02)
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