- Hydroxamic Acids as Chemoselective (ortho-Amino)arylation Reagents via Sigmatropic Rearrangement
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The use of readily available hydroxamic acids as reagents for the chemoselective (ortho-amino)arylation of amides is described. This reaction proceeds under metal-free, mild conditions, displays a very broad scope, and constitutes a direct approach for the metal-free attachment of aniline residues to carbonyl derivatives.
- Shaaban, Saad,Tona, Veronica,Peng, Bo,Maulide, Nuno
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p. 10938 - 10941
(2017/08/30)
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- TRIFLUOROMETHOXYLATION OF ARENES VIA INTRAMOLECULAR TRIFLUOROMETHOXY GROUP MIGRATION
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The present invention provides a process of producing a trifluoromethoxylated aryl or trifluoromethoxylated heteroaryl having the structure: (I), wherein A is an aryl or heteroaryl, each with or without subsutitution; and R1 is -H, -(alkyl), -(alkenyl), -(alkynyl), -(aryl), -(heteroaryl), - (alkylaryl), - (alkylheteroaryl), -NH-(alkyl), -N(alkyl)2, -NH-(alkenyl), -NH-(alkynyl) -NH-(aryl), -NH-(heteroaryl), -O-(alkyl), -O-(alkenyl), -O-(alkynyl), -O-(aryl), -O-(heteroaryl), -S-(alkyl), -S- (alkenyl), -S-(alkynyl), -S-(aryl), or -S-(heteroaryl), comprising: (a) reacting a compound having the structure: (II), with a trifluoromethylating agent in the presence of a base in a first suitable solvent under conditions to produce a compound having the structure: (III); and (b) maintaining the compound produced in step (a) in a second suitable solvent under conditions sufficient to produce the trifluoromethoxylated aryl or trifluormethoxylated heteroaryl having the structure: (I).
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- Mechanistic studies on intramolecular C-H trifluoromethoxylation of (hetero)arenes via OCF3-migration
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The one-pot two-step intramolecular aryl and heteroaryl C-H trifluoromethoxylation recently reported by our group has provided a general, scalable, and operationally simple approach to access a wide range of unprecedented and valuable OCF3-containing building blocks. Herein we describe our investigations to elucidate its reaction mechanism. Experimental data indicate that the O-trifluoromethylation of N-(hetero)aryl-N-hydroxylamine derivatives is a radical process, whereas the OCF3-migration step proceeds via a heterolytic cleavage of the N-OCF3 bond followed by rapid recombination of a short-lived ion pair. Computational studies further support the proposed ion pair reaction pathway for the OCF3-migration process. We hope that the current study would provide useful insights for the development of new transformations using versatile N-(hetero)aryl-N-hydroxylamine synthons.
- Lee, Katarzyna N.,Lei, Zhen,Morales-Rivera, Cristian A.,Liu, Peng,Ngai, Ming-Yu
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p. 5599 - 5605
(2016/07/06)
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- Rhodium(III)-catalyzed internal oxidative coupling of N-hydroxyanilides with alkenes via C-H activation
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Abstract Described herein is an efficient new method for ortho-olefination of anilides in the presence of AgSbF6 and NaOAc via rhodium(III)-catalyzed internal oxidative C-H bond activation based on hydroxyl as directing and oxidative group. A range of alkenes and functional groups on acetanilides is supported and a possible mechanism is proposed according to the experimental results.
- Wen, Jing,Wu, An,Chen, Pei,Zhu, Jin
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supporting information
p. 5282 - 5286
(2015/08/26)
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- Trifluoromethoxylation of arenes: Synthesis of ortho- Trifluoromethoxylated aniline derivatives by OCF3 migration
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Aryl trifluoromethoxylation by a two-step sequence of O-trifluoromethylation of N-aryl-N-hydroxylamine derivatives and intramolecular OCF3 migration is presented. This protocol allows easy access to a wide range of synthetically useful ortho-OCF3 aniline derivatives. In addition, it utilizes bench-stable reagents, is operationally simple, shows high functional-group tolerance, and is amenable to gram-scale as well as one-pot synthesis.Areaction mechanism of a heterolytic cleavage of the N-OCF3 bond followed by recombination of the resulting nitrenium ion and trifluoromethoxide is proposed for the OCF3-migration reaction.
- Hojczyk, Katarzyna N.,Feng, Pengju,Zhan, Chengbo,Ngai, Ming-Yu
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p. 14559 - 14563
(2015/01/09)
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- Laccase Variants
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The present invention relates to variants of a parent laccase. The present invention also relates to polynucleotides encoding the variant laccases and to nucleic acid constructs, vectors, and host cells comprising the polynucleotides, and methods of using the variant enzymes.
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- ANTIMICROBIAL COMPOSITION CONTAINING AN OXIDOREDUCTASE AND AN ENHANCER OF THER N-HYDROXYANILIDE-TYPE
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The present invention relates to an enzymatic composition capable of killing or inhibiting microbial cells or micro-organisms, e.g. in laundry, on hard surfaces, in water systems, on skin, on teeth or on mucous membranes. The present invention also relate
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- Temperature-Dependent Acid Dissociation Constants (Ka, ΔHa, ΔSa) for a Series of Nitrogen-Substituted Hydroxamic Acids in Aqueous Solution
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The acid dissociation constants (Ka) of a series of eight substituted N-phenylacetohydroxamic acids, CH3C-(O)N(OH)C6H4X (X=H, 4-CH3, 4-Cl, 4-I, 3-I, 3-CN, 4-CN, 4-C(O)CH3), have been determined in aqueous solution (I=2.0) for a range of temperatures.The pKa data at 25 deg C exhibit a small variation with the substituent X in the direction expected according to their Hammett substituent constants (ρ ca. 0.1).These small variations in pKa values are due to compensating trends in ΔHa and ΔSa, which show significant variation with substituent.These results are discussed in terms of the substituent's influence on hydroxamate anion-solvent interactions and the relative influence on pKa of a substituted phenyl group attached to the C or N end of the hydroxamate moiety.
- Poth Brink, Christina,Crumbliss, Alvin L.
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p. 1171 - 1176
(2007/10/02)
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