- Iron-Catalyzed Enantioselective Radical Carboazidation and Diazidation of α,β-Unsaturated Carbonyl Compounds
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Azidation of alkenes is an efficient protocol to synthesize organic azides which are important structural motifs in organic synthesis. Enantioselective radical azidation, as a useful strategy to install a C-N3 bond, remains challenging due to the inherently instability and unique structure of radicals. Here, we disclose an efficient enantioselective radical carboazidation and diazidation of α,β-unsaturated ketones and amides catalyzed by chiral N,N′-dioxide/Fe(OTf)2 complexes. An array of substituted alkenes was transformed to the corresponding α-azido carbonyl derivatives in good to excellent enantioselectivities, benefiting the preparation of chiral α-amino ketones, vicinal amino alcohols, and vicinal diamines. Control experiments and mechanistic studies proved the radical pathway in the reaction process. The DFT calculations showed that the azido transferred to the radical intermediate via an intramolecular five-membered transition state with the internal nitrogen of the Fe-N3 species.
- Dong, Shunxi,Feng, Xiaoming,He, Jun,Liu, Wen,Liu, Xiaohua,Pu, Maoping,Wu, Yun-Dong,Zhang, Tinghui
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supporting information
p. 11856 - 11863
(2021/08/16)
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- ANTIMICROBIAL COMPOUNDS AND METHODS
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The invention is directed to compounds that are active as antibacterial agents. The invention compounds are active against gram-positive and gram-negative bacteria and can be used to treat infections caused by gram-positive and gram-negative bacteria. Also disclosed are processes and intermediates for making the compounds.
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Paragraph 00448; 00659
(2020/07/31)
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- Stereoselective synthesis of 2-aryl-4-en-1-ols, promising synthons for the preparation of oxygen heterocycles
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Reactions of arylacetic acids with N-methoxymethanamine afford corresponding Weinreb amides which at alkenylation with methallyl and prenyl bromides in the presence of (Me3Si)2N–Na+ form unsaturated amides ArCHRCONMe(OMe) (R = CH2CMe=CH2, CH2C=CMe2). Amides readily react with BuLi and BnMgCl to give ketones ArCHRCOR' (R' = Bu, Bn). A stereoselective reduction of the latter with LiBH(s-Bu)3 leads to a quantitative formation of syn-isomers of 2-aryl-4-en-1-ols.
- Boev,Moskalenko,Belopukhov,Nikonova
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p. 169 - 177
(2017/04/21)
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- Enantioselective Mannich Reaction Employing 1,3,5-Triaryl-1,3,5-triazinanes Catalyzed by Chiral-at-Metal Rhodium Complexes
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Chiral-at-metal RhIII complexes catalyze the efficient enantioselective Mannich reaction of 2-acyl imidazoles with 1,3,5-triazinanes, affording the corresponding adducts in 81–99 % yield with up to >99 % enantioselectivity. This protocol performs with 0.1 mol-% of RhIII complex on gram scale without any loss in enantioselectivity.
- Gong, Jun,Li, Shi-Wu,Qurban, Saira,Kang, Qiang
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supporting information
p. 3584 - 3593
(2017/07/22)
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- Iron-Catalyzed Michael Addition of Ketones to Polar Olefins
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The base metal complex tetrabutylammonium nitrosyltricarbonylferrate {Bu4N[Fe(CO)3(NO)] (TBA[Fe])} – catalyzes the conjugate addition of ketones to polar olefins. The reaction is applicable to a wide range of substrates leading to interesting building blocks for organic synthesis. Clear indications for an acid-base type rather than a C?H activation pathway exist. (Figure presented.).
- Zhang, Di-Han,Knelles, Jakob,Plietker, Bernd
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supporting information
p. 2469 - 2479
(2016/08/16)
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- Enantioselective Synthesis of syn-α-Aryl-β-hydroxy Weinreb Amides: Catalytic Asymmetric Roskamp Reaction of α-Aryl Diazo Weinreb Amides
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A convenient one-pot procedure to synthesize a variety of highly optically active syn-α-aryl-β-hydroxy Weinreb amides using an asymmetric Roskamp/reduction strategy is described. An oxazaborolidinium ion catalyzed asymmetric Roskamp reaction of α-aryl diazo Weinreb amides with aldehydes produced α-phenyl-β-keto Weinreb amides, which were in situ reduced with zinc borohydride to give syn-α-aryl-β-hydroxy Weinreb amides in good yields (up to 87%) with high enantioselectivities (up to 99% ee) and syn stereoselectivities (>20:1).
- Shin, Sung Ho,Baek, Eun Hee,Hwang, Geum-Sook,Ryu, Do Hyun
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supporting information
p. 4746 - 4749
(2015/10/12)
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- Aerobic Asymmetric Dehydrogenative Cross-Coupling between Two C sp 3 -H Groups Catalyzed by a Chiral-at-Metal Rhodium Complex
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A sustainable C-C bond formation is merged with the catalytic asymmetric generation of one or two stereocenters. The introduced catalytic asymmetric cross-coupling of two Csp3-H groups with molecular oxygen as the oxidant profits from the oxidative robustness of a chiral-at-metal rhodium(III) catalyst and exploits an autoxidation mechanism or visible-light photosensitized oxidation. In the latter case, the catalyst serves a dual function, namely as a chiral Lewis acid for catalyzing enantioselective enolate chemistry and at the same time as a visible-light-driven photoredox catalyst. Green stuff: A sustainable C-C bond formation is merged with the catalytic asymmetric generation of one or two stereocenters by combining asymmetric enolate chemistry with either autoxidation or visible-light photosensitized oxidation. The robustness of a chiral-at-metal rhodium(III) catalyst serves to facilitate the reaction. PMP=para-methoxyphenyl, TFA=trifluoroacetic acid.
- Tan, Yuqi,Yuan, Wei,Gong, Lei,Meggers, Eric
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supporting information
p. 13045 - 13048
(2015/11/02)
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- On the reactivity of imidazole carbamates and ureas and their use as esterification and amidation reagents
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The optimization, substrate scope, and mechanism of esterification and amidation of carboxylic acids mediated by imidazole-based reagents are discussed. The innate reactivity of carbonylimidazole reagents with a range of nucleophiles is also explored. New reagents developed for the synthesis of α,β-unsaturated esters are described, as are reagents for the preparation of tertiary amides directly from carboxylic acids.
- Heller, Stephen T.,Sarpong, Richmond
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experimental part
p. 8851 - 8859
(2011/12/02)
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- Chemoselective esterification and amidation of carboxylic acids with imidazole carbamates and ureas
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Imidazole carbamates and ureas were found to be chemoselective esterification and amidation reagents. A wide variety of carboxylic acids were converted to their ester or amide analogues by a simple synthetic procedure in high yields.
- Heller, Stephen T.,Sarpong, Richmond
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supporting information; experimental part
p. 4572 - 4575
(2010/12/25)
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- N-HYDROXYACRYLAMIDE COMPOUNDS
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This invention relates to novel N-hydroxyacrylamide compounds of formula (I) and pharmaceutically acceptable salts thereof . More particularly, it relates to novel N-hydroxyacrylamide compounds and pharmaceutically acceptable salts thereof which act as a
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Page/Page column 35
(2008/06/13)
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