Palladium Catalyzed C–H Functionalization of <i>O</i>-Arylcarbamates: Selective <i>ortho</i>-Bromination Using NBS

John, Alex; Nicholas, Kenneth M.

doi:10.1021/jo300713h

Cited by 85 publications

(41 citation statements)

References 53 publications

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“…Liu and co-workers also explored the olefination of phenol carbamates with styrenes. [27] Halogenation The Pd-catalyzed ortho-bromination andc hlorination of phenol carbamates with N-bromosuccinimide and N-chlorosuccinimide were reported by Nicholas's group [29] and Rao's group, [30] re-Scheme18. Pd II -catalyzed ortho-arylation of carbamate-protected phenols.…”

Section: Olefinationmentioning

confidence: 99%

“…The Pd‐catalyzed ortho ‐bromination and chlorination of phenol carbamates with N ‐bromosuccinimide and N ‐chlorosuccinimide were reported by Nicholas's group and Rao's group, respectively (Scheme ). Both methods required the use of p ‐toluenesulfonic acid to activate the N ‐halosuccinimides, consequently enhancing the efficiency of the ortho ‐halogenation reaction.…”

Section: Ortho‐c−h Activation Of Phenolsmentioning

confidence: 99%

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Transition Metal‐Catalyzed Directing‐Group‐Assisted C−H Activation of Phenols

Luo

2019

ChemSusChem

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Strategies that exploit directing groups to control the site selectivity in the C−H activation of arenes have received much attention during the past two decades. In light of the importance of phenol derivatives in the areas of pharmaceuticals, agrochemicals, and materials science, transition‐metal‐catalyzed C−H activation of phenols has proven to be an extremely useful tool in organic synthesis. This Minireview summarizes the current state‐of‐the‐art direct C−H activation of phenol derivatives under transition‐metal catalysis.

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Section: Olefinationmentioning

confidence: 99%

Section: Ortho‐c−h Activation Of Phenolsmentioning

confidence: 99%

Transition Metal‐Catalyzed Directing‐Group‐Assisted C−H Activation of Phenols

Luo

2019

ChemSusChem

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“…136 Nicholas demonstrated that protected brominated phenols could be accessed from the corresponding O-arylcarbamates via a Pd-catalyzed oxidative C−H bromination (Scheme 46). 137 Although the authors initially attempted to achieve an ortho-C− H amination reaction, after unsuccessful attempts, they observed that stoichiometric iodination of the corresponding cyclopalladated O-phenyl carbamates could be achieved using NIS. However, when attempting to achieve a catalytic process, they observed a significant background reaction occurred which afforded the undesired para-brominated product.…”

Section: Scheme 32 Pd-catalyzed Ortho-selective C−h Halogenation Of mentioning

confidence: 99%

“…This latter finding was contested in a subsequent publication by Grushin, 179 wherein it was reasoned that the Meisenheimer-type aryl group contained in the ArPd(II)F complex found to undergo carbon−fluorine bond reductive elimination could simply be undergoing a nucleophilic S N Ar reaction with free F − to generate the observed aryl halide. Accordingly, Grushin and co-workers synthesized and characterized analogs of this ArPd(II)F dimer (where Ar = p-NO 2 −C 6 H 4 ), 137 where Ar was a nonMeisenheimer type aromatic and possessed an H, Me, or OMe group (86a−c, Figure 5) from the corresponding ArPd(II)I analogs 85a−c.…”

Section: Carbon−halogen Reductive Elimination From Pd(ii) Complexesmentioning

confidence: 99%

Modern Transition-Metal-Catalyzed Carbon–Halogen Bond Formation

2016

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The high utility of halogenated organic compounds has prompted the development of a vast number of transformations which install the carbon-halogen motif. Traditional routes to these building blocks have commonly involved multiple steps, harsh reaction conditions, and the use of stoichiometric and/or toxic reagents. In this regard, using transition metals to catalyze the synthesis of organohalides has become a mature field in itself, and applying these technologies has allowed for a decrease in the production of waste, higher levels of regio- and stereoselectivity, and the ability to produce enantioenriched target compounds. Furthermore, transition metals offer the distinct advantage of possessing a diverse spectrum of mechanistic possibilities which translate to the capability to apply new substrate classes and afford novel and difficult-to-access structures. This Review provides comprehensive coverage of modern transition metal-catalyzed syntheses of organohalides via a diverse array of mechanisms. Attention is given to the seminal stoichiometric organometallic studies which led to the corresponding catalytic processes being realized. By breaking this field down into the synthesis of aryl, vinyl, and alkyl halides, it becomes clear which methods have surfaced as most favored for each individual class. In general, a pronounced shift toward the use of C-H bonds as key functional groups, in addition to methods which proceed by catalytic, radical-based mechanisms has occurred. Although always evolving, this field appears to be heading in the direction of using starting materials with a significantly lower degree of prefunctionalization in addition to less expensive and abundant metal catalysts.

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“…We prepared a panel of new palladacycles carrying the various directing groups (Table 1). The pivaloylanilide palladacycle 3 , 20 the phenylurea palladacycle 4 , 21, 22 the phenol ester palladacycle 5 , 23 and the O -phenylcarbamate palladacycle 6 24 were prepared according to the published procedures. On the other hand, the N -phenylcarbamate palladacycles 7 – 20 were prepared by treating the corresponding carbamate with Pd(OAc) 2 and triflic acid in dichloroethane or dioxane at room temperature (see Table S1 in the Supplemental Information for yields).…”

mentioning

confidence: 99%