Nickel-Catalyzed Decarboxylation of Aryl Carbamates for Converting Phenols into Aromatic Amines

Nishizawa, Akihiro; Takahira, Tsuyoshi; Yasui, Kosuke; Fujimoto, Hayato; Iwai, Tomohiro; Sawamura, Masaya; Chatani, Naoto; Tobisu, Mamoru

doi:10.1021/jacs.9b02751

Cited by 48 publications

(34 citation statements)

References 30 publications

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“…This observation is noteworthy, as it indicates that the reactivity can be externally modulated via an intermolecular proton transfer step, thus providing an additional control element. In line with previous reports 32 and the steric demand of diisopropylamide as well as tert-butanol, an outer-sphere mechanism via nickel species II could offer a plausible explanation (Fig. 4b 6).…”

Section: Fig 4 Extension Of Reactivity Working Hypothesis and Preliminary Mechanistic Experiments A: Nies In Other Reactions;supporting

confidence: 89%

“…However, due to the fundamental role of the base in coupling reactions, such base-free protocols are scarce, with isolated examples reported for coupling partners like diazonium salts 24,25 or fluorinated compounds 26 , along with decarbonylative [27][28][29] , directed 30,31 or intramolecular approaches 32 . Thus, there is currently no general solution to this long-standing challenge in catalysis.…”

Section: Main Textmentioning

confidence: 99%

“…For the BHA and the MHR, carbamate 4 under conditions III afforded amine 9 and alkene 10 in promising initial yields of 54% and 36%, respectively. After assessment of different parameters, the more sterically hindered carbamate 12 was found to deliver superior results in comparison to carbamate 4 by preventing deleterious intramolecular amination 32 . Further, in the case of the BHA, a change of the ligand to 3,4-bis(dicyclohexylphosphaneyl)thiophene (dcypt) 41 led to a highly efficient process starting from equimolar amounts of carbamate 12 and aniline 6 yielding amine 9 almost quantitatively.…”

Section: Main Textmentioning

confidence: 99%

“…Electron-deficient substrates (32)(33)(34)(35)(36) afforded the products in almost quantitative yields, whereas electron-rich ones (31,(39)(40)(41) required slight adjustments of the reaction conditions to provide satisfactory results. Furthermore, various functional groups were compatible including electrophilic ones such as nitriles (33), esters (34,43) and ketones (35,41).…”

Section: Main Textmentioning

confidence: 99%

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Non-Innocent Electrophiles Unlock Exogenous Base-Free Coupling Reactions

Toupalas¹,

Morandi

2021

Preprint

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Transition metal catalysis has revolutionized our ability to precisely manipulate matter and has placed itself at the forefront of the combat against societal challenges through key discoveries in drug design, agriculture, material synthesis and environmental sciences. Numerous important transition metal catalyzed reactions rely on stoichiometric quantities of an exogenous base to enable catalytic turnover. Despite playing a fundamental role, paradoxically, the base poses major challenges on several fronts, such as restricting the accessible chemical space due to functional group incompatibilities, or causing heterogeneous reaction mixtures that affect reproducibility, scale-up campaigns, and the implementation of emerging technologies, e.g. flow chemistry or high-throughput experimentation. Ultimately, this impedes innovation across multiple areas. Here we introduce a unifying strategy that eliminates the need for an exogenous base through the use of non-innocent electrophiles (NIE). Key to its success was the encryption of the base into the electrophile rendering it non-innocent, thus preserving the synthetic utility of the original reaction while overcoming the challenges associated with the exogenous base. The use of nickel as an earth-abundant metal catalyst as well as the employment of ubiquitous phenol derivatives as non-innocent electrophiles are further salient features of this sustainable protocol. The universal applicability of this concept was demonstrated by turning multiple traditionally base-dependent catalytic reactions, e.g. the Buchwald-Hartwig amination, the Mizoroki-Heck reaction and the Suzuki-Miyaura coupling, into exogenous base-free homogeneous processes. In a broader context, the results presented in this work provide a conceptual blueprint for the utilization of non-innocent electrophiles to overcome core limitations and unlock novel features in catalysis.

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Section: Fig 4 Extension Of Reactivity Working Hypothesis and Preliminary Mechanistic Experiments A: Nies In Other Reactions;supporting

confidence: 89%

Section: Main Textmentioning

confidence: 99%

Section: Main Textmentioning

confidence: 99%

Section: Main Textmentioning

confidence: 99%

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Non-Innocent Electrophiles Unlock Exogenous Base-Free Coupling Reactions

Toupalas¹,

Morandi

2021

Preprint

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“…The sterically demanding DPPBz-type ligand SciOPP showed al igand effect similar to DPPBz (65 %, entry 14). The polystyrene-cross-linking DPPBz-type ligand,P S-DPPBz, the utility of which was previously demonstrated in our studies on Cu catalysis, [23] was much lesse ffective than the parents oluble ligand DPPBz (5 %, entry 15). Monodentate ligands sucha sP Cy 3 and IPr did not give an efficient catalyst( entries 16 and 17).…”

mentioning

confidence: 67%

Nickel‐Copper‐Catalyzed Hydroacylation of Vinylarenes with Acyl Fluorides and Hydrosilanes

Ueda

Iwai

Sawamura

2019

Chemistry A European J

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The hydroacylation of vinylarenesw ith acyl fluorides and hydrosilanes was enabled by as ynergistic bimetallic Ni/Cu-catalytic system, giving access to the corresponding branched ketone products. The reaction takes place under mild conditions at 25-80 8Ca nd tolerates base-sensitive functional groups such as methoxycarbonyl and acetoxy groups.Acyl fluorides, which are easily preparedf rom carboxylic acids, [1] are less common as acylatingr eagents than the corresponding chlorides and bromides due to their inertness as acylating reagents under conventional conditions. However,t he use of acyl fluoridesa sr eagents in organic synthesis through activation of the CÀFb ond have attracted growing interest in recent years, offering new types of molecular transformations that have not been achieved with acyl chlorideso rb romides. Generally,t he fluorides show better tolerance towards nucleophilic or basic functional groups than the chlorides and bromides.Apioneering work by Rovis described an efficient ketone synthesis through Ni-catalyzed cross-coupling of acyl fluorides with organozincs( Scheme 1a). [2] Later,O giwaraa nd Sakai reported similart ransformationsu sing organosiliconso r organoborons by Pd catalysis. [3] These reactions were initiated by oxidativea ddition of the acyl C(sp 2 )ÀFb onds to low-valent metal complexes,producing acyl metal intermediates. [4,5] Catalytic in situ generation of nucleophilic organometallic speciesb yi nsertiono fu nsaturated CÀCb onds to MÀXb onds followed by trapping with acyl electrophiles affords attractive synthetic methods, which can avoid the use of stoichiometric amountso fp re-formed organometallic reagents. [6] Metal-catalyzed reductivec ouplingo fC ÀCu nsaturated compounds with electrophiles is representative. [7,8] For acylation,c arboxylic anhydrides were used as acylating electrophiles in the reactiono f vinylarenes in the presence of hydrosilanes or H 2 as H sources. [6a, 7a,b] More recently,G agosz and Riant used acyl fluorides as acylating reagents for the Cu-catalyzed boroacylation of alleneswith bis(pinacolato)diboron (Scheme 1b). [9] Our long-standing interest in synergistic bimetallic catalysis prompted us to explore the possibility of enabling the hydroacylation of vinylarenes with acyl fluorides and hydrosilanes by synergistic Ni/Cu two-metal catalysis. [10][11][12][13][14][15] As shown in Scheme 1c,a na cyl fluoridei sa ctivated through oxidative addition to aN i(0) complex (step a). Concurrently,avinylarene is converted into an ucleophilic alkylcopper speciesb yi nsertion into aC u ÀHs pecies( hydrocupration, step d) [16] that is generated in situ from aC u ÀFs peciesw ith ah ydrosilane (step e). [17] The two catalytic speciesm eet and transmetalation occurs to give the corresponding diorganonickel(II) complex with simultaneous regeneration of the CuÀFs pecies (step b). Finally,r e-[a] Prof. Dr.M.S awamura Institute for Chemical Reaction Design and Discovery (WPI-ICReDD)

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Regioselective Synthesis of Fused Furans by Decarboxylative Annulation of α,β‐Alkenyl Carboxylic Acid with Cyclic Ketone: Synthesis of Di‐Heteroaryl Derivatives

et al. 2019

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a,b-Alkenyl carboxylicacids undergo Cu II -mediated decarboxylative annulation reactions with aliphatic cyclic ketones to provides ynthetically valuable di-heterocycles.T he annulation process tolerates avariety of aliphatic ketones and heterocyclic alkenyl carboxylic acids,p roducing substituted fused furan derivatives with complete regioselectivity.T he current protocol offers as ynthetically applicable pathway to construct avariety of oligo-heterocycles through Cu-mediated single-electron transfer and decarboxylation. Notably,s ynthesis of relatively inaccessible di-heterocycles has been achieved successfully using this protocol.

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Nickel-Catalyzed Decarboxylation of Aryl Carbamates for Converting Phenols into Aromatic Amines

Cited by 48 publications

References 30 publications

Non-Innocent Electrophiles Unlock Exogenous Base-Free Coupling Reactions

Non-Innocent Electrophiles Unlock Exogenous Base-Free Coupling Reactions

Nickel‐Copper‐Catalyzed Hydroacylation of Vinylarenes with Acyl Fluorides and Hydrosilanes

Regioselective Synthesis of Fused Furans by Decarboxylative Annulation of α,β‐Alkenyl Carboxylic Acid with Cyclic Ketone: Synthesis of Di‐Heteroaryl Derivatives

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