- Meta Selective C-H Borylation of Sterically Biased and Unbiased Substrates Directed by Electrostatic Interaction
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An electrostatically directed meta borylation of sterically biased and unbiased substrates is described. The borylation follows an electrostatic interaction between the partially positive and negative charges between the ligand and substrate. With this strategy, it has been demonstrated that a wide number of challenging substrates, especially 4-substituted substrates, can selectively be borylated at the meta position. Moreover, unsubstituted substrates also displayed excellent meta selectivity. The reaction employs a bench-stable ligand and proceeds at a milder temperature, precluding the need to synthesize a bulky and sophisticated ligand/template.
- Chaturvedi, Jagriti,Haldar, Chabush,Bisht, Ranjana,Pandey, Gajanan,Chattopadhyay, Buddhadeb
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supporting information
p. 7604 - 7611
(2021/05/26)
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- Weak coordinated nitrogen functionality enabled regioselective C-H alkynylationviaPd(ii)/mono-N-protected amino acid catalysis
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The exploration of weak coordinated amine derivative enabled regioselective C-H functionalization remains challenging due to the elusive achievement of reactivity and selectivity simultaneously. Herein, regioselective C-H alkynylation of various readily transformable nitrogen functionalities was developed with great efficiency, with the assistance of the mono-N-protected amino acid (MPAA) ligandviaPd(ii) catalysis proceedingvia5, 6 and 7-membered palladacycle intermediates.
- Liu, Bifu,Ouyang, Wensen,Nie, Jianhong,Gao, Yang,Feng, Kejun,Huo, Yanping,Chen, Qian,Li, Xianwei
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supporting information
p. 11255 - 11258
(2020/10/06)
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- Sulfoxide ligand metal catalyzed oxidation of olefins
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The enantioselective synthesis of isochroman motifs has been accomplished via Pd(II)-catalyzed allylic C—H oxidation from terminal olefin precursors. Critical to the success of this goal was the development and utilization of a novel chiral aryl sulfoxide-oxazoline (ArSOX) ligand. The allylic C—H oxidation reaction proceeds with the broadest scope and highest levels asymmetric induction reported to date (avg. 92% ee, 13 examples ≥90% ee). Additionally, C(sp3)-N fragment coupling reaction between abundant terminal olefins and N-triflyl protected aliphatic and aromatic amines via Pd(II)/sulfoxide (SOX) catalyzed intermolecular allylic C—H amination is disclosed. A range of 52 allylic amines are furnished in good yields (avg. 76%) and excellent regio- and stereoselectivity (avg. >20:1 linear:branched, >20:1 E:Z). For the first time, a variety of singly activated aromatic and aliphatic nitrogen nucleophiles, including ones with stereochemical elements, can be used in fragment coupling stiochiometries for intermolecular C—H amination reactions.
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Page/Page column 118-119
(2019/05/09)
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- Palladium-Catalyzed, Enantioselective Formal Cycloaddition between Benzyltriflamides and Allenes: Straightforward Access to Enantioenriched Isoquinolines
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Benzyl and allyltriflamides can engage in Pd-catalyzed oxidative (4+2) annulations with allenes, to produce highly valuable tetrahydroisoquinoline or dihydropyridine skeletons. The reaction is especially efficient when carried out in the presence of designed N-protected amino acids as metal ligands. More importantly, using this type of chiral ligands, it is possible to perform desymmetrizing, annulative C-H activations of prochiral diarylmethylphenyl amides, and thus obtain the corresponding isoquinolines with high enantiomeric ratios.
- Vidal, Xandro,Mascare?as, José L.,Gulías, Moisés
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supporting information
p. 1862 - 1866
(2019/01/30)
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- Triflamides: Highly Reactive, Electronically Activated N-Sulfonyl Amides in Catalytic N-C(O) Amide Cross-Coupling
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The direct, highly chemoselective Suzuki-Miyaura cross-coupling of trifluoromethanesulfonamides (triflamides) by selective N-C(O) amide bond cleavage is reported. This operationally simple, mild, and user-friendly method accomplishes the direct synthesis of ketones from amides by a catalytic manifold as a powerful alternative to Weinreb amides. Mechanistic studies support rotational inversion and electronic activation, favoring selective insertion under mild conditions. Our data strongly suggest that triflamides should be routinely considered as precursors in amide bond cross-coupling.
- Shi, Shicheng,Lalancette, Roger,Szostak, Roman,Szostak, Michal
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supporting information
p. 1253 - 1257
(2019/02/26)
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- C-H to C-N Cross-Coupling of Sulfonamides with Olefins
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Cross-coupling of nitrogen with hydrocarbons under fragment coupling conditions stands to significantly impact chemical synthesis. Herein, we disclose a C(sp3)-N fragment coupling reaction between terminal olefins and N-triflyl protected aliphatic and aromatic amines via Pd(II)/SOX (sulfoxide-oxazoline) catalyzed intermolecular allylic C-H amination. A range of (56) allylic amines are furnished in good yields (avg. 75%) and excellent regio- and stereoselectivity (avg. >20:1 linear:branched, >20:1 E:Z). Mechanistic studies reveal that the SOX ligand framework is effective at promoting functionalization by supporting cationic π-allyl Pd.
- Ma, Rulin,Christina White
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supporting information
p. 3202 - 3205
(2018/03/13)
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- Metal-free C-H sulfonamidation of pyrroles by visible light photoredox catalysis
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We report a one-step procedure for the preparation of N-(2-pyrrole)-sulfonamides from sulfonamides and pyrroles. The reaction uses visible light, an acridinium dye as photocatalyst and oxygen as the terminal oxidant for the oxidative C-N bond formation; structures of several reaction products were confirmed by X-ray structure analysis. The reaction is selective for pyrroles, due to the available oxidation power of the photocatalyst and the required stability of the carbocation intermediate under the reaction conditions.
- Meyer, Andreas Uwe,Berger, Anna Lucia,K?nig, Burkhard
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supporting information
p. 10918 - 10921
(2016/09/09)
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- Ligand-promoted ortho-C-H amination with Pd catalysts
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2,4,6-Trimethoxypyridine is identified as an efficient ligand for promoting a Pd-catalyzed ortho-C-H amination of both benzamides and triflyl-protected benzylamines. This finding provides guidance for the development of ligands that can improve or enable PdII-catalyzed Csp2-H activation reactions directed by weakly coordinating functional groups.
- Zhu, Dajian,Yang, Guoqiang,He, Jian,Chu, Ling,Chen, Gang,Gong, Wei,Chen, Ke,Eastgate, Martin D.,Yu, Jin-Quan
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supporting information
p. 2497 - 2500
(2015/02/19)
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- PALLADIUM-CATALYZED ORTHO-FLUORINATION
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A new method of ortho-fluorination where an aryl C—H bond is directly replaced by an aryl C-F bond in a palladium-catalyzed reaction is provided. The method includes the ortho-fluorination of a triflamide protected benzylamine, a palladium catalyst, such as Pd(OTf)2, a fluorinating reagent such as N-fluoro-2,4,6-trimethylpyridinium triflate, and a ligand to promote the reaction such as N-methylpyrrolidinone (NMP).
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Page/Page column 12
(2012/03/26)
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- Determination of pKa values of fluoroalkanesulfonamides and investigation of their nucleophilicity
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The pKa values of a series of fluoroalkanesulfonylamides were measured by potentiometric titration. Different kinds of alkyl halides and tosylates were employed to investigate the nucleophilicity of fluoroalkanesulfonylamides. Fluoroalkanesulfonylamides with longer fluoroalkyl chain have weaker nucleophilicity.
- Zhang, Cheng-Pan,Wang, Zong-Ling,Chen, Qing-Yun,Zhang, Chun-Tao,Gu, Yu-Cheng,Xiao, Ji-Chang
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experimental part
p. 761 - 766
(2010/08/06)
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- Versatile Pd(OTf)2·2H2O-catalyzed ortho-fluorination using NMP as a promoter
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(Chemical Equation Presented) Pd(OTf)2·2H 2O-catalyzed ortho-fluorination of triflamide-protected benzylamines is reported. The use of N-fluoro-2,4,6-trimethylpyridinium triflate as the F+ source and NMP as a promoter is crucial for this reaction. The conversion of triflamide into a wide range of synthetically useful functional groups makes this fluorination protocol broadly applicable in medicinal chemistry and synthesis.
- Wang, Xisheng,Mei, Tian-Sheng,Yu, Jin-Quan
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supporting information; experimental part
p. 7520 - 7521
(2009/10/17)
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- Electronic and steric effects in thermal denitrosation of N-nitrosoamides
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N-Alkyl-N-nitrosoamides undergo competitive reactions whose rates are dependent upon the interplay of a number of factors. There already exists a significant body of work delineating the effects of pH on the partitioning of the nitrosoamides along their deaminative (-N2) and denitrosative (- NO+ ) pathways. In this paper, the issue of pH dependence is discussed with particular attention to nitrosoamide decompositions in nonaqueous media. The role of the acidity of the medium in the partitioning of the nitrosoamide between deamination and denitrosation and in the choice of deaminative pathways is revisited. In nonaqueous media under near-neutral conditions, the partitioning's pH dependence is evidently accompanied by a sensitivity to structural features in the nitrosoamide. Thus, diminution of steric crowding around the N-nitroso moiety as well as the presence of strongly electron-withdrawing acyl units (i.e., those derived from strong acids, e.g., tosyl and trifyl) increase the relative yield of amides by encouraging the denitrosative pathway. A mechanism for thermal denitrosation of nitrosoamides under near-neutral conditions is proposed in which rapid protonation at the acyl O rather than slow protonation at the amidic N is the first step in the reaction profile. A rate-limiting, bimolecular reaction between the O-conjugate acid and adventitious nucleophiles at the nitrosyl group then occurs followed by rapid tautomerization to amide.
- Darbeau,Perez,Sobieski,Rose,Yates,Boese,Darbeau
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p. 5679 - 5686
(2007/10/03)
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- β-Tosylethylamine: A Useful Reagent for Preparation of N-Protected Amides, Carbamates, and Related Compounds. Application to Synthesis of β-Lactams
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Readily prepared β-tosylethylamine (3) can be used to synthesize N-tosylethyl (TSE)-protected amido compounds and β-lactams, which can be deprotected under mild conditions with potassium tert-butoxide.
- DiPietro, Darren,Borzilleri, Robert M.,Weinreb, Steven M.
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p. 5856 - 5857
(2007/10/02)
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