- Palladium(II)-Catalyzed Enantioselective Synthesis of α-(Trifluoromethyl)arylmethylamines
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We describe a method for the synthesis of α-(trifluoromethyl)arylmethylamines that consists of the palladium(II)-catalyzed addition of arylboroxines to imines derived from trifluoroacetaldehyde. Palladium acetate is used as a catalyst with electron-neutral or electron-rich arylboroxines, and it was found that addition of an ammonium or silver salt was crucial to promote the reaction of electron-poor boroxines. With (S)-t-Bu-PyOX as the chiral ligand, this method delivers a variety of α-trifluoromethylated amines in 57-91% yield and with greater than 92% ee in most cases.
- Johnson, Thomas,Luo, Bo,Lautens, Mark
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p. 4923 - 4930
(2016/07/06)
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- Oxidative coupling of aryl boron reagents with sp3-carbon nucleophiles: The enolate chan–evans–lam reaction
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Reported is a versatile new oxidative method for the arylation of activated methylene species. Under mild reaction conditions (RT to 40°C), Cu(OTf)2mediates the selective coupling of functionalized aryl boron species with a variety of stabilized sp3-nucleophiles. Tertiary malonates and amido esters can be employed as substrates to generate quaternary centers. Complementing either traditional cross-coupling or SNAr protocols, the transformation is chemoselective in the presence of halogen electrophiles, including aryl bromides and iodides. Substrates bearing amide, sulfonyl, and phosphonyl groups, which are not amenable to coupling under mild Hurtley-type conditions, are suitable reaction partners.
- Moon, Patrick J.,Halperin, Heather M.,Lundgren, Rylan J.
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supporting information
p. 1894 - 1898
(2016/12/03)
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- Oxidative Heck desymmetrisation of 2,2-disubstituted cyclopentene-1,3-diones
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Oxidative Heck couplings have been successfully developed for 2,2-disubstituted cyclopentene-1,3-diones. The direct coupling onto the 2,2-disubstituted cyclopentene-1,3-dione core provides a novel expedient way of enantioselectively desymmetrising all-carbon quaternary centres. This journal is
- Walker,Lamb,Beattie,Nikodemiak,Lee
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supporting information
p. 4089 - 4092
(2015/03/30)
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- Diastereoselective synthesis of vicinally bis(trifluoromethylated) alkylboron compounds through successive insertions of 2,2,2-trifluorodiazoethane
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The usefulness of embedded CF3 substituents within organic substructures necessitates the development of diverse methods for incorporating this functional group. A recently reported route to α-trifluoromethylated alkylboron compounds by an α-transfer mechanism has now been extended to the synthesis of unprecedented, vicinally ditrifluoromethylated alkylboron compounds in a diastereoselective fashion. The utility of these products is highlighted by conversion of the C-B bond into other functional groups.
- Molander, Gary A.,Ryu, Da Weon
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supporting information
p. 14181 - 14185
(2015/02/19)
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- Scalable synthesis of oxazolones from propargylic alcohols through multistep palladium(II) catalysis: β-selective oxidative heck coupling of cyclic sulfonyl enamides and aryl boroxines
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A whale of a scale: The title oxidative Heck coupling proceeded with unusual β selectivity to generate a variety of branched substituted oxazolones (see scheme; Ts=p-toluenesulfonyl). The three-step synthesis from readily available starting materials with a simple palladium catalyst and inexpensive reagents could be carried out in a single reaction vessel or scaled up for the preparation of large amounts of these amino acid precursors. Copyright
- Alamsetti, Santosh Kumar,Persson, Andreas K. A.,Jiang, Tuo,Baeckvall, Jan-E.
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supporting information
p. 13745 - 13750
(2014/01/06)
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- Transition-metal-free electrophilic amination of arylboroxines
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A transition-metal-free strategy to construct C(sp2)-N bonds using arylboroxines and O-benzoyl hydroxylamines as coupling partners has been developed. This transformation provides a useful method to access various aromatic amines.
- Xiao, Qing,Tian, Leiming,Tan, Renchang,Xia, Ying,Qiu, Di,Zhang, Yan,Wang, Jianbo
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supporting information; experimental part
p. 4230 - 4233
(2012/09/22)
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- Mild and ligand-free Pd(II)-catalyzed conjugate additions to hindered γ-substituted cyclohexenones
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Ligand-free cationic Pd(II) catalyst with NaNO3 as an additive is a highly active catalytic system for conjugate additions to sterically hindered γ-substituted cyclohexenones. More challenging γγ- and βγ-substrates also react well to produce products with quaternary centers in good dr. The conjugate additions occur in a diastereoselective fashion under mild, practical and air-stable conditions, using readily available commercial reagents.
- Jordan-Hore, James A.,Sanderson, James N.,Lee, Ai-Lan
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supporting information; scheme or table
p. 2508 - 2511
(2012/07/03)
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- Rh-catalyzed addition of arylboroxines to cyclic N -(Isopropanesulfinyl) ketimines
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Arylboroxines, which are easily accessed by drying commercially available arylboronic acids, are added to N-(isopropanesulfinyl)ketimines derived from cyclohexanone, N-Boc-piperidin-4-one, and tetrahydropyran-4-one in high yields and with excellent functional group compatibility via rhodium catalysis. These results contrast with additions to the corresponding ketimines incorporating the larger N-tert-butanesulfinyl group, which give considerably lower yields. Efficient two-step preparation of racemic isopropanesulfinamide from inexpensive isopropyl disulfide and recycling of the isopropanesulfinyl group from the addition products are also described.
- Jung, Hyung Hoon,Buesking, Andrew W.,Ellman, Jonathan A.
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p. 9593 - 9600,8
(2012/12/12)
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- Rh-catalyzed addition of arylboroxines to cyclic N -(Isopropanesulfinyl) ketimines
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Arylboroxines, which are easily accessed by drying commercially available arylboronic acids, are added to N-(isopropanesulfinyl)ketimines derived from cyclohexanone, N-Boc-piperidin-4-one, and tetrahydropyran-4-one in high yields and with excellent functional group compatibility via rhodium catalysis. These results contrast with additions to the corresponding ketimines incorporating the larger N-tert-butanesulfinyl group, which give considerably lower yields. Efficient two-step preparation of racemic isopropanesulfinamide from inexpensive isopropyl disulfide and recycling of the isopropanesulfinyl group from the addition products are also described.
- Jung, Hyung Hoon,Buesking, Andrew W.,Ellman, Jonathan A.
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p. 9593 - 9600
(2013/01/15)
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- Palladium-catalyzed cascade reaction for the synthesis of substituted isoindolines
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Arylate then cyclize: A palladium(II)-catalyzed cascade sequence has been developed to provide highly diastereomerically enriched cis-1-aryl-3-vinyl isoindolines (see scheme). The method uses commercially available aryl boronic acids and boroxine compounds containing a variety of electron-rich, -neutral, or -poor aromatic groups. Ts=4-toluenesulfonyl. Copyright
- Williams, Florence J.,Jarvo, Elizabeth R.
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supporting information; experimental part
p. 4459 - 4462
(2011/06/26)
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- Highly functional group compatible Rh-catalyzed addition of arylboroxines to activated N-tert-butanesulfinyl ketimines
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The rhodium-catalyzed addition of readily accessible arylboroxines to N-tert-butanesulfinyl ketimines derived from oxetan-3-one, N-Boc-azetidin-3-one, and isatins proceeds in high yields with excellent functional group compatibility. Moreover, high diastereoselectivities are observed for the additions to the N-sulfinyl ketimines derived from isatins.
- Jung, Hyung Hoon,Buesking, Andrew W.,Ellman, Jonathan A.
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supporting information; experimental part
p. 3912 - 3915
(2011/09/16)
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- Chiral tetrafluorobenzobarrelenes as effective ligands for rhodium-catalyzed asymmetric 1,4-addition of arylboroxines to β,β-disubstituted α,β-unsaturated ketones
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(Chemical Equotion Present) Lock, Stock and Two Smoking Barrelenes: The rhodium-catalyzed 1,4-addition of readily available arylboronic acid anhydrides to simple β,β-disubstituted α,βunsaturated ketones creates quaternary carbon stereocenters with high enantiomeric excesses using a chiral tetrafluorobenzobarrelene ligand.
- Shintani, Ryo,Takeda, Momotaro,Nishimura, Takahiro,Hayashi, Tamio
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supporting information; experimental part
p. 3969 - 3971
(2010/09/03)
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- Chiral 1,1′-binaphthylazepine-derived amino alcohol catalyzed asymmetric aryl transfer reactions with boroxine as aryl source
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Using chiral 1,1′-binaphthylazepine-derived amino alcohol as catalyst, the direct addition of in situ prepared arylzinc (with triphenylboroxine as aryl source) to various aryl aldehydes can afford optically active diarylmethanols in high yields and enantioselectivities (up to 96%).
- Liu, Can,Guo, Zong-Liang,Weng, Jiang,Lu, Gui,Chan, Albert S. C.
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experimental part
p. 159 - 164
(2010/09/04)
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- Arylation and vinylation of α-diazocarbonyl compounds with boroxines
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An alternative approach for α-arylation and α-vinylation of carbonyl compounds is described: reaction between aryl-or vinylboroxines with α-diazocarbonyl compounds leads to the formation of α-arylated or α-vinylated carbonyl compounds under mild conditions.
- Peng, Cheng,Zhang, Wei,Yan, Guobing,Wang, Jianbo
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supporting information; experimental part
p. 1667 - 1670
(2009/08/07)
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