- Photoenzymatic Synthesis of α-Tertiary Amines by Engineered Flavin-Dependent "ene"-Reductases
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α-Tertiary amines are a common motif in pharmaceutically important molecules but are challenging to prepare using asymmetric catalysis. Here, we demonstrate engineered flavin-dependent ‘ene'-reductases (EREDs) can catalyze radical additions into oximes to prepare this motif. Two different EREDs were evolved into competent catalysts for this transformation with high levels of stereoselectivity. Mechanistic studies indicate that the oxime contributes to the enzyme templated charge-transfer complex formed between the substrate and cofactor. These products can be further derivatized to prepare a variety of motifs, highlighting the versatility of ERED photoenzymatic catalysis for organic synthesis.
- Gao, Xin,Turek-Herman, Joshua R.,Choi, Young Joo,Cohen, Ryan D.,Hyster, Todd K.
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supporting information
p. 19643 - 19647
(2021/12/01)
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- MAYTANSINOID ANALOGS AS ANTITUMOR AGENTS
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Ansamycin analogs, including maytansinoid analogs, and their use in treating cell proliferative diseases and conditions, and in particular, for use as antitumor agents.
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Page/Page column 9
(2008/06/13)
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- S4N4SbCl5 complex: a useful reagent for conversion of sterically less hindred α-bromo ketones to α-chloro ketones
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The reactions of sterically less hindered α-bromo alkyl and aryl ketones with tetrasulfur tetranitride antimony pentachloride (S4N4SbCl5) complex in toluene at reflux gave the corresponding α-chloro kerones in good to excellent yields.
- Kim, Kil-Joong,Kim, Kyongtae
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p. 4227 - 4230
(2007/10/03)
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- Preparation of 1-aminoalkylphosphonic acids and 2-aminoalkylphosphonic acids by reductive amination of oxoalkylphosphonates
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By reacting dialkyl 1-oxo- or 2-oxoalkylphosphonates with benzhydrylamine followed by reduction with triacetoxyborohydride and acid hydrolysis gave corresponding aminoalkylphosphonic acids with satisfactory yields. The use of benzylamine, α-methylbenzylamine and tritylamine was unsuccessful in the case of dialkyl 1-oxoalkylphosphonates whereas conversion of 2-oxoalkylphosphonates was also achieved although with lower yields.
- Ryglowski, Artur,Kafarski, Pawel
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p. 10685 - 10692
(2007/10/03)
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- Process for the preparation of 3-(2-chloro-2-(4-chloro-phenyl)-vinyl)-2,2-dimethylcyclopropanecarboxylic acid
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3-(2-chloro-2-(4-chloro-phenyl)-vinyl)2,2-dimethylcyclopropanecarboxylic acid and its derivatives are obtained by reactive 3-chloro-3(4-chlorophenyl)-propenal with chloromethyl isopropyl ketone in a first step and reacting the resulting 4,4-dimethyl-1,3,6-trichloro-1-(4-chlorophenyl)- hex-1-en-5-one, optionally without isolation, in the presence of aqueous bases or in the presence of alkoxides. The resulting carboxylic acids or carboxylic acid esters can be converted into their derivatives such as, for example, salts, esters, amides or halides by generally known methods.
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- PRODUCTION OF 1,1,1-TRIHALOGENO-2-ALKANOLS AND SOME OF THEIR PROPERTIES
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The reaction of acyclic and carbocyclic carbonyl compounds with haloforms was studied in liquid ammonia and dimethylformamide in the presence of basic catalysts (t-BuOK, KOH).As a result of the reaction 1,1,1-trihalogeno-2-alkanols were obtained.They were used for the synthesis of 1,1,1-trihalogeno-2-methoxyalkanes, 1,1-dibromoalkenes, 1,1-dichloro-2-methoxyalkenes, and alkyl mono- and dichloromethyl ketones.
- Bal'on, Ya. G.,Shul'man, M. D.,Vakulenko, L. I.
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p. 1231 - 1237
(2007/10/02)
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- Preparation of monochloromethyl ketones
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A process for the production of a monochloromethyl ketone of the formula STR1 in which R1, R2 and R3 each independently is a hydrogen atom or an optionally substituted alkyl, alkenyl, alkinyl or aryl radical, or R1 and R2 together with the carbon atom to which they are attached form an optionally substituted carbocyclic ring, comprising reacting a 1,1-dichloroalkene of the formula STR2 with a phenolate of the formula STR3 in which R4 each independently is a halogen atom, a nitro group, or an optionally substituted alkyl, alkoxy or aryl radical, n is 0, 1, 2 or 3, and M is one equivalent of an alkali metal ion or alkaline earth metal ion, thereby to obtain a phenyl ether intermediate, and then subjecting the phenyl ether intermediate to an acid hydrolysis. The products are useful as intermediates in the synthesis of fungicides.
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- Addition of 4-Chlorobenzenesulphenyl Chloride to 3-Methylbut-1-yne, Hex-1-yne, and Phenylacetylene: Isomerisation and Hydrolysis of the Adducts
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The addition of (4-ClC6H4SCl, (2), to RCH(*)CH, (1; R=Pri, Bun), gives (E)-4-ClC6H4(R)C(*)C(H)Cl, (E)-(3), and (E)-4-ClC6H4(H)C(*)C(R)Cl, (E)-(4) in a fixed ratio; the addition to (1; R=Ph) gives regiospecifically (E)-(3; R=Ph) in ethyl acetate, but different proportions of (E)-(3) and (E)-(4) (R=Ph), in chloroform, sym-tetrachloroethane, and acetic acid.With an excess of the sulphenyl chloride (2), (E)-(3) and (E)-(4) isomerize to (Z)-(4) (same R).The sulphuric-acid catalysed hydrolysis of (E)-(3; R=Pri, Bun, Ph) gives α-chloroketones RCOCH2Cl(5) (same R).The (E)-(4) isomers do not hydrolyse.
- Capozzi, Giuseppe,Romeo, Giovanni,Lucchini, Vittorio,Modena, Giorgio
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p. 831 - 836
(2007/10/02)
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- β-Substituted Organolithium Compounds from Chlorohydrins: Application to the Direct Synthesis of Bifunctionalized Organic Cpmpounds
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The reaction of different chlorohydrins with n-butyl-lithium at -78 deg C followed by metallation wiht lithium naphthalenide at the same temperature leads to very reactive organolithium compounds bearing an alkoxide function at the β-position with respect to metal.The reaction of these intermediates with several electriphiles leads to mono- as well as bi-functionalized organic compounds.Thus, treatment of these dianions with deuterium oxide, oxygen, carbon dioxide, benzyl bromide, dimethyl disulphide, and carbonyl compounds, gave 2-deuterioalcohols, 1,2-diols, β-hydroxy-acids, 2-benzyl alcohols, 2-hydroxy-thioethers, and 1,3-diols respectively.The preparation of β-substituted organolithium derivatives can be alternatively carried out starting from α-chloroketones by the same procedure.When the lithium atom is linked to a secondary carbon atom the dianions are very unstable and decompose, even at -100 deg C, by β-elimination yielding the corresponding olefins.
- Barluenga, Jose,Florez, Josefa,Yus, Miguel
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p. 3019 - 3026
(2007/10/02)
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- Reaction of 2-Chlorooxiranes with Phosphites and Phosphanes: A New Route to β-Carbonylphosphonic Esters and -phosphonium Salts
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Reaction of alkylsubstituted 2-chlorooxiranes 6 with trialkyl phosphites 11 gives β-carbonylphosphonic diesters (12a, b, 15a, b, 20a, 21a), free of isomeric enol phosphates or α,β-epoxyphosphonates. 2-Chloro-2-(chloromethyl)oxirane (6c) undergoes with 11 an Arbusov reaction followed by a Perkow reaction ( -> 18 -> 17).The limitation of the method is probed with sterically crowded substituents in 3-position of 6. 6b yields with triphenylphosphane a β-ketophosphonium salt (23), which can be converted to a keto-ylide (24).
- Herzig, Christian,Gasteiger, Johann
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p. 601 - 614
(2007/10/02)
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- Chlorination of Aliphatic Ketones in Methanol
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The chlorination of aliphatic ketones in methanol has been examined.The product distributions in methanol differ substantially from those obtained by chlorination in carbon tetrachloride.The reaction in methanol favors addition of chlorine to the least substituted carbon α to the carbonyl group.The effect is especially pronounced if an α carbon bearing two substituents is present.The distribution of products is determined by the relative stability of the enol ethers formed from the ketone under the reaction conditions.
- Gallucci, R. R.,Going, R.
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p. 2532 - 2538
(2007/10/02)
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