- Access to α-Cyano Carbonyls Bearing a Quaternary Carbon Center by Reductive Cyanation
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Reductive cyanation of tertiary alkyl bromides using electrophilic cyanating reagent and zinc reductant was developed, providing various α-cyano ketones, esters, and carboxamides containing a nitrile-bearing all-carbon quaternary center in good to excellent yields under mild reaction conditions. The corresponding reaction mechanism involving in situ generated organozinc reagent and reactivity distinction was elucidated by density functional theory computation.
- Ren, Xinyi,Shen, Chaoren,Wang, Guangzhu,Shi, Zhanglin,Tian, Xinxin,Dong, Kaiwu
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supporting information
p. 2527 - 2532
(2021/05/05)
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- A Highly Efficient Method for the Bromination of Alkenes, Alkynes and Ketones Using Dimethyl Sulfoxide and Oxalyl Bromide
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The pairing of DMSO and oxalyl bromide is reported as a highly efficient brominating reagent for various alkenes, alkynes and ketones. This bromination approach demonstrates remarkable advantages, such as mild conditions, low cost, short reaction times, provides excellent yields in most cases and represents a very attractive alternative for the preparation of dibromides and α-bromoketones.
- Ding, Rui,Li, Jiaqi,Jiao, Wenyi,Han, Mengru,Liu, Yongguo,Tian, Hongyu,Sun, Baoguo
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p. 4325 - 4335
(2018/11/21)
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- Iron-Catalyzed Acyl Migration of Tertiary α-Azidyl Ketones: Synthetic Approach toward Enamides and Isoquinolones
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This paper reports that tertiary α-azidyl phenyl ketones can be transformed into enamides by treatment with FeBr2 at elevated temperature in DMF. The reaction proceeds via 1,2-benzoyl migration from α-carbon to the nitrogen atom, accompanied by expulsion of a nitrogen molecule. This protocol is suitable for the synthesis of N-(cyclopent-1-en-1-yl)benzamides, N-(cyclohex-1-en-1-yl)benzamides, and N-benzoyl-α-methyl enamines and provides a convenient approach toward isoquinolones.
- Yang, Tonghao,Fan, Xing,Zhao, Xiaopeng,Yu, Wei
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supporting information
p. 1875 - 1879
(2018/04/16)
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- Catalytic dehydrogenative dual functionalization of ethers: Dealkylation-oxidation-bromination accompanied by C-O bond cleavage: Via aerobic oxidation of bromide
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Catalytic dehydrogenative dual functionalization (DDF) of ethers via oxidation, dealkylation, and α-bromination by the aerobic oxidation of bromide was developed to obtain the corresponding α-bromo ketones in high yields. In particular, the reaction of substituted tetrahydrofurans as cyclic ethers provided 3,3-dibromo tetrahydrofuran-2-ols in high yields selectively through the double α-bromination.
- Moriyama, Katsuhiko,Hamada, Tsukasa,Nakamura, Yu,Togo, Hideo
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supporting information
p. 6565 - 6568
(2017/07/10)
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- Stereoselective Traceless Borylation–Allenation of Propargylic Epoxides: Dual Role of the Copper Catalyst
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Chiral α-allenols are prepared with high diastereocontrol through an unprecedented and spontaneous β-oxygen elimination of an α-epoxy vinyl boronate. Stochiometric experiments and DFT calculations support a dual role of the copper catalyst, which orchestrates the hydroboration and the syn-elimination step.
- Jarava-Barrera, Carlos,Parra, Alejandro,Amenós, Laura,Arroyo, Ana,Tortosa, Mariola
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supporting information
p. 17478 - 17481
(2017/11/30)
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- Building Congested Ketone: Substituted Hantzsch Ester and Nitrile as Alkylation Reagents in Photoredox Catalysis
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For the first time, 4-alkyl Hantzsch esters were used to construct molecules with all-carbon quaternary centers by visible light-induced photoredox catalysis via transfer alkylation. Up to a 1500 h-1 turnover frequency was achieved in this reaction. Reactions of 4-alkyl Hantzsch nitriles as tertiary radical donors joined two contiguous all-carbon quaternary centers intermolecularly, and this chemistry was used to synthesize a common precursor of a class of hydroxysteroid dehydrogenase inhibitors.
- Chen, Wenxin,Liu, Zheng,Tian, Jiaqi,Li, Jin,Ma, Jing,Cheng, Xu,Li, Guigen
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supporting information
p. 12312 - 12315
(2016/10/07)
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- Efficient bromination of olefins, alkynes, and ketones with dimethyl sulfoxide and hydrobromic acid
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The oxidative bromination of olefins, alkynes, and ketones has been developed with HBr as the brominating reagent and DMSO as the mild oxidant. The simple conditions, high bromide-atom-economy, as well as easy accessibility and low cost of DMSO and HBr make the present strategy prospective for the synthesis of dibrominated alkanes, dibrominated alkenes and α-bromoketones.
- Song, Song,Li, Xinwei,Sun, Xiang,Yuan, Yizhi,Jiao, Ning
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supporting information
p. 3285 - 3289
(2015/06/25)
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- An alternative reaction outcome in the gold-catalyzed rearrangement of 1-alkynyloxiranes
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The gold(III)-catalyzed rearrangement of tetrasubstituted 1-alkynyloxiranes is described. This transformation led to a different reaction outcome with respect to related substrates previously studied. Thus, tertiary α-alkynylketones or alkynols can be selectively obtained. Moreover, gold(III) proved capable to catalyze the rearrangement of simple epoxides. These results indicate that gold(III) complexes act as oxophilic Lewis acids rather than π-acids in these transformations.
- Gonzalez, Maria J.,Gonzalez, Jesus,Vicente, Ruben
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supporting information
p. 6140 - 6143,4
(2020/09/16)
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- PROCESS FOR THE PREPARATION OF AROMATIC ALPHA-HYDROXY KETONES
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Process for the preparation of aromatic alpha-hydroxyketones (aromatic α-hydroxyketones) that does not require the use of chlorine, sulfuryl chloride or bromine and comprises the halogenation of an intermediate aromatic ketone with a hydrogen halide in the presence of an oxidising compound.
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- CF3CO2ZnEt-mediated highly regioselective rearrangement of bromohydrins to aldehydes
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A highly efficient and selective rearrangement reaction of bromohydrins to aldehydes mediated by CF3CO2ZnEt was described. The secondary and tertiary aldehydes were prepared under mild conditions in good to excellent yields (85-99%). The scope and limitations of this rearrangement process were also investigated.
- Wang, Zhihui,Li, Meiyi,Zhang, Wenqin,Jia, Jiangnan,Wang, Fei,Xue, Song
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supporting information; experimental part
p. 5968 - 5971
(2011/11/29)
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- PROCESS FOR THE PREPARATION OF AROMATIC ALPHA-HYDROXY KETONES
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Process for the preparation of aromatic alpha-hydroxyketones (aromatic α- hydroxyketones) that does not require the use of chlorine, sulfuryl chloride or bromine and comprises the halogenation of an intermediate aromatic ketone with a hydrogen halide in the presence of an oxidising compound.
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Page/Page column 17
(2010/01/29)
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- Rates of Acid- and Base-Catalyzed Enolization of trans-Hexahydrofluorenone. Concerning Stereoelectronic Control of Enolization
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Rates of both acid-catalyzed and base-catalyzed enolization of trans-hexahydrofluorenone (trans-HHF) have been measured and compared with those for a variety of other ketones.It was found that trans-HHF enolizes substantially faster than cyclohexyl phenyl ketone (CPK) in both acid (1800-fold) and base (2650-fold).This rate variation is thought to be due to two factors. (1) In trans-HHF the cleaving C-H bond is held rigidly parallel to the ? orbital of the ketone.About a factor of 25- to 60-fold is attributed to this stereoelectronic effect. (2) There are stericinteractions in the enol of CPK which decrease its rate of enolization by about 40- to 50-fold.
- Pollack, Ralph M.,Kayser, Robert H.,Cashen, Michael J.
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p. 3983 - 3987
(2007/10/02)
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