- Radical C?H Trifluoromethoxylation of (Hetero)arenes with Bis(trifluoromethyl)peroxide
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Trifluoromethoxylated (hetero)arenes are of great interest for several disciplines, especially in agro- and medicinal chemistry. Radical C?H trifluoromethoxylation of (hetero)arenes represents an attractive approach to prepare such compounds, but the high cost and low atom economy of existing .OCF3 radical sources make them unsuitable for the large-scale synthesis of trifluoromethoxylated building blocks. Herein, we introduce bis(trifluoromethyl)peroxide (BTMP, CF3OOCF3) as a practical and efficient trifluoromethoxylating reagent that is easily accessible from inexpensive bulk chemicals. Using either visible light photoredox or TEMPO catalysis, trifluoromethoxylated arenes could be prepared in good yields under mild conditions directly from unactivated aromatics. Moreover, TEMPO catalysis allowed for the one-step synthesis of valuable pyridine derivatives, which have been previously prepared via multi-step approaches.
- Dix, Stefan,Golz, Paul,Schmid, Jonas R.,Riedel, Sebastian,Hopkinson, Matthew N.
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supporting information
p. 11554 - 11558
(2021/07/09)
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- Mild Copper-Catalyzed Addition of Arylboronic Esters to Di- tert -butyl Dicarbonate: An Easy Access to Methyl Arylcarboxylates
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An efficient copper-catalyzed addition of arylboronic esters to (Boc) 2O was developed. The reaction can be conducted under exceedingly mild conditions and is compatible with a variety of synthetically relevant functional groups. It therefore represents a useful alternative route for the synthesis of methyl arylcarboxylates. A preliminary mechanistic study indicated the involvement of an addition-elimination mechanism.
- Xu, Jin-Di,Su, Xiao-Bo,Wang, Cai,Yao, Li-Wei,Liu, Jing-Hui,Hu, Guo-Qin
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supporting information
p. 833 - 837
(2021/02/26)
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- Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow
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The first example of photocatalytic trifluoromethoxylation of arenes and heteroarenes under continuous-flow conditions is described. Application of continuous-flow microreactor technology allowed to reduce the residence time up to 16 times in comparison t
- Cendón, Borja,Gulías, Moisés,Ho, Michelle,No?l, Timothy,Nyuchev, Alexander V.,Sambiagio, Carlo,Struijs, Job J. C.,Wan, Ting,Wang, Ying
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supporting information
p. 1305 - 1312
(2020/07/10)
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- Redox-Neutral TEMPO Catalysis: Direct Radical (Hetero)Aryl C?H Di- and Trifluoromethoxylation
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Applications of TEMPO. catalysis for the development of redox-neutral transformations are rare. Reported here is the first TEMPO.-catalyzed, redox-neutral C?H di- and trifluoromethoxylation of (hetero)arenes. The reaction exhibits a broad substrate scope, has high functional-group tolerance, and can be employed for the late-stage functionalization of complex druglike molecules. Kinetic measurements, isolation and resubjection of catalytic intermediates, UV/Vis studies, and DFT calculations support the proposed oxidative TEMPO./TEMPO+ redox catalytic cycle. Mechanistic studies also suggest that Li2CO3 plays an important role in preventing catalyst deactivation. These findings will provide new insights into the design and development of novel reactions through redox-neutral TEMPO. catalysis.
- Lee, Johnny W.,Lim, Sanghyun,Maienshein, Daniel N.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 21475 - 21480
(2020/10/02)
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- Silver-Mediated Trifluoromethoxylation of (Hetero)aryldiazonium Tetrafluoroborates
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Here we report a silver-mediated trifluoromethoxylation of (hetero)aryldiazonium tetrafluoroborates by converting an aromatic amino group into an OCF3 group. This method, which can be considered to be a trifluoromethoxylation variation of the classic Sandmeyer-type reaction, uses readily available aryl and heteroaromatic amines as starting materials and AgOCF3 as trifluoromethoxylating reagents. The broad substrate scope and simple, mild reaction condition made this transformation a valuable method in constructing aryl-OCF3 bonds.
- Yang, Yu-Ming,Yao, Jian-Fei,Yan, Wei,Luo, Zhuangzhu,Tang, Zhen-Yu
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supporting information
p. 8003 - 8007
(2019/10/11)
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- DIFLUOROMETHOXYLATION AND TRIFLUOROMETHOXYLATION COMPOSITIONS AND METHODS FOR SYNTHESIZING SAME
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The present invention provides a compound having the structure (I), a processing of making the compound; and a process of using the compound as a reagent for the difluoromethoxylation and trifluoromethoxylation of arenes or heteroarenes.
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Page/Page column 75; 79; 118-119; 124-125
(2019/09/18)
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- Redox-Active Reagents for Photocatalytic Generation of the OCF3 Radical and (Hetero)Aryl C?H Trifluoromethoxylation
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The trifluoromethoxy (OCF3) radical is of great importance in organic chemistry. Yet, the catalytic and selective generation of this radical at room temperature and pressure remains a longstanding challenge. Herein, the design and development of a redox-active cationic reagent (1) that enables the formation of the OCF3 radical in a controllable, selective, and catalytic fashion under visible-light photocatalytic conditions is reported. More importantly, the reagent allows catalytic, intermolecular C?H trifluoromethoxylation of a broad array of (hetero)arenes and biorelevant compounds. Experimental and computational studies suggest single electron transfer (SET) from excited photoredox catalysts to 1 resulting in exclusive liberation of the OCF3 radical. Addition of this radical to (hetero)arenes gives trifluoromethoxylated cyclohexadienyl radicals that are oxidized and deprotonated to afford the products of trifluoromethoxylation.
- Zheng, Weijia,Lee, Johnny W.,Morales-Rivera, Cristian A.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 13795 - 13799
(2018/09/27)
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- Radical Trifluoromethoxylation of Arenes Triggered by a Visible-Light-Mediated N?O Bond Redox Fragmentation
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A simple trifluoromethoxylation method enables non-directed functionalization of C?H bonds on a range of substrates, providing access to aryl trifluoromethyl ethers. This light-driven process is distinctly different from conventional procedures and occurs through an OCF3 radical mechanism mediated by a photoredox catalyst, which triggers an N?O bond fragmentation. The pyridinium-based trifluoromethoxylation reagent is bench-stable and provides access to synthetic diversity in lead compounds in an operationally simple manner.
- Jelier, Benson J.,Tripet, Pascal F.,Pietrasiak, Ewa,Franzoni, Ivan,Jeschke, Gunnar,Togni, Antonio
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supporting information
p. 13784 - 13789
(2018/09/14)
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- Catalytic C?H Trifluoromethoxylation of Arenes and Heteroarenes
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The intermolecular C?H trifluoromethoxylation of arenes remains a long-standing and unsolved problem in organic synthesis. Herein, we report the first catalytic protocol employing a novel trifluoromethoxylating reagent and redox-active catalysts for the direct (hetero)aryl C?H trifluoromethoxylation. Our approach is operationally simple, proceeds at room temperature, uses easy-to-handle reagents, requires only 0.03 mol % of redox-active catalysts, does not need specialized reaction apparatus, and tolerates a wide variety of functional groups and complex structures such as sugars and natural product derivatives. Importantly, both ground-state and photoexcited redox-active catalysts are effective. Detailed computational and experimental studies suggest a unique reaction pathway where photoexcitation of the trifluoromethoxylating reagent releases the OCF3 radical that is trapped by (hetero)arenes. The resulting cyclohexadienyl radicals are oxidized by redox-active catalysts and deprotonated to form the desired products of trifluoromethoxylation.
- Zheng, Weijia,Morales-Rivera, Cristian A.,Lee, Johnny W.,Liu, Peng,Ngai, Ming-Yu
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supporting information
p. 9645 - 9649
(2018/03/21)
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- Fluorodecarboxylation for the Synthesis of Trifluoromethyl Aryl Ethers
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The synthesis of mono-, di-, and trifluoromethyl aryl ethers by fluorodecarboxylation of the corresponding carboxylic acids is reported. AgF2induces decarboxylation of aryloxydifluoroacetic acids, and AgF, either generated in situ or added separately, serves as a source of fluorine to generate the fluorodecarboxylation products. The addition of 2,6-difluoropyridine increased the reactivity of AgF2, thereby increasing the range of functional groups and electronic properties of the aryl groups that are tolerated. The reaction conditions used for the formation of trifluoromethyl aryl ethers also served to form difluoromethyl and monofluoromethyl aryl ethers.
- Zhang, Qing-Wei,Brusoe, Andrew T.,Mascitti, Vincent,Hesp, Kevin D.,Blakemore, David C.,Kohrt, Jeffrey T.,Hartwig, John F.
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supporting information
p. 9758 - 9762
(2016/08/10)
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- A convenient synthesis of trifluoromethyl ethers by oxidative desulfurization-fluorination of dithiocarbonates
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Trifluoromethyl ethers R-OCF3 are easily synthesized from the corresponding dithiocarbonates R-OCS2Me (R = aryl or primary alkyl) by a reagent system consisting of 70% HF/pyridine and an N-halo imide. When the reaction is applied to R-OCS2Me wherein R = secondary alkyl, tertiary alkyl, or benzylic group, fluorination leading to the corresponding alkyl fluorides R-F is achieved, whereas a combination of 50% HF/pyridine and N- bromosuccinimide affords the corresponding trifluoromethyl ethers R-OCF3 (R = secondary).
- Kanie, Kiyoshi,Tanaka, Yoichiro,Suzuki, Kazundo,Kuroboshi, Manabu,Hiyama, Tamejiro
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p. 471 - 484
(2007/10/03)
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- Oxidative desulfurization-fluorination of xanthates. A convenient synthesis of trifluoromethyl ethers and difluoro (methylthio)methyl ethers
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Treatment of xanthates R-OC(S)SMe with (HF)9/Py and 1,3-dibromo-5,5-dimethylhydantoin gives trifluoromethyl ethers R-OCF3 through intermediates R-OCF2SMe, which could be isolated upon treatment of xanthates with n-Bu4N+H2F3- and N-bromosuccinimide.
- Kuroboshi, Manabu,Suzuki, Kazundo,Hiyama, Tamejiro
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p. 4173 - 4176
(2007/10/02)
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