Amination

Jun 11, 2018 - A cascade C–H arylation/amination protocol using homoallylic primary amines as the starting materials in the presence of a palladium ...
0 downloads 0 Views 348KB Size
Download PDF
Subscriber access provided by Kaohsiung Medical University

Letter

Dual Role of Aryl Iodide in Cascade C–H Arylation/Amination: Arylation Reagent and Cocatalyst for C–N formation Deng-Yuan Li, Shuo Liu, Shuang Chen, An Wang, Xiao-Ping Zhu, and Pei Nian Liu ACS Catal., Just Accepted Manuscript • Publication Date (Web): 11 Jun 2018 Downloaded from http://pubs.acs.org on June 11, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Catalysis

Dual Role of Aryl Iodide in Cascade C–H Arylation/Amination: Arylation Reagent and Cocatalyst for C–N formation Deng-Yuan Li, Shuo Liu, Shuang Chen, An Wang, Xiao-Ping Zhu, and Pei-Nian Liu* Shanghai Key Laboratory of Functional Materials Chemistry, Key Lab for Advanced Materials and School of Chemistry & Molecular Engineering, East China University of Science and Technology, Meilong Road 130, Shanghai, 200237, China ABSTRACT: A cascade C−H arylation/amination protocol using homoallylic primary amines as the starting materials in the presence of a palladium catalyst produces 2-aryl-1-pyrrolines with excellent regioselectivity and in good yields. Mechanistic studies indicate that this transformation proceeds via palladium-catalyzed Heck coupling, C−H amination, and tautomerization. As an unprecedented example of aryl iodide acting as an arylation reagent and a cocatalyst, the key role of aryl iodide as a cocatalyst is to generate the active bivalent aryl palladium catalyst to promote C−N formation during the C−H amination step. KEYWORDS c0catalysis • aryl iodides • primary amines • C−H amination • cascade reactions

Intramolecular selective C−H amination has emerged as a powerful tool for concise, atom-economical construction of new N-heterocycles, which are highly prevalent in various nitrogen-containing biologically active compounds and pharmaceuticals.1 Earlier synthetic routes to construct N-heterocycles can be traced back to the Hofmann–Löffler–Freytag reaction,2 which converts acyclic amines into pyrrolidines through homolysis of a preformed haloamine in refluxing acid. Another efficient approach is a strong base-promoted oxidative C−N coupling reaction that involves deprotonation of the N−H and C−H bonds to form the dianion and subsequent oxidation of dianion.3 These harsh reaction conditions led to unsatisfactory scope of substrates and restricted their application in the synthesis. Over the past several decades, transition-metal-catalyzed C−H activation has proven to be a viable strategy to provide more efficient routes to access these heterocycles. Specifically, the intramolecular C−H insertion of metallated amides and nitrenes has been applied for the synthesis of highly complex alkaloids.4 Although some catalytic systems have been well developed recently for transition-metalcatalyzed C−H amination/cyclization reactions,5,6 most of them require either different types of N-protected amides such as amides and sulfonamides,5 or harsh oxidative systems including metal oxidants,6 hypervalent iodine(III) reagents,7 peroxides or persulfates8 to sustain the catalytic cycle. Therefore, the development of new catalytic systems that function under relatively mild conditions and compatible with primary amines is highly desirable. In recent years, aryl iodide-mediated reactions have become increasingly important in the synthesis of C−C,9 C−O,10 and C−N11 bonds. Kita developed the first aryl iodide-catalyzed C−H amination/cyclization process via the dearomatization of arenes.12a,b Since then, aryl iodidemediated C−N bond formation was extensively used to

construct various N-heterocyclic scaffolds, including pyrrolidines,12c γ-lactams,12d and carbazoles.12e However, the use of peroxides for the in situ conversion of aryl iodides into hypervalent iodine(III), which serves as the actual catalyst, was required, thus limiting the utility of those approaches. On the other hand, aryl iodide as a primary arylation reagent is widely utilized in transition-metalcatalyzed arylation. In general, the aryl iodide is known to undergo an oxidative addition with a transition metal to form a hypervalent metal center, followed by a selective aryl reductive elimination to yield the arylation product.13 To the best of our knowledge, however, the aryl iodide as a cocatalyst in a transition-metal-catalyzed C−H activation has not been reported to date. Scheme 1. Cascade C−H Arylation/Amination

Substituted 1-pyrrolines are important five-membered N-heterocycles used extensively in agrochemical and pharmaceutical applications. Therefore, it is highly desirable to develop general and practical methodologies to access these heterobicyclic structures.14 Recently, Bower developed enantioselective Narasaka–Heck cyclizations to access to 1-pyrrolidines containing tetrasubstituted nitrogen-bearing stereocenters.14a Selander reported nickelcatalyzed 1,2-aminoarylation of oximeester-tethered alkenes with boronic acids for the synthesis of pyrrolines.14b Using the similar strategy, Studer reported photoredox neutral alkene carboimination to access 1-pyrrolines.14c

ACS Paragon Plus Environment

ACS Catalysis 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Most of these methods used α-imino-oxy acids as the coupling partner of alkenes during the formation of 1pyrrolines. Much less progress has been made towards transformation of homoallylic primary amines into 1pyrrolines via oxidative amination.14d,e Our group is interested in the construction of heterocycles by using a combination of cascade-based catalysis and C−H activation.15 Here, we report a palladiumcatalyzed cascade C−H arylation/amination of homoallylic amines to afford 2-aryl-1-pyrrolines with excellent regioselectivity and in good yields (Scheme 1). The mechanistic studies suggested that the aryl iodide could act as an arylation reagent in the C−H arylation step, and as a cocatalyst to promote C−N formation during the C−H amination step. This is the first example that demonstrates the dual ability of aryl iodides in C−H activation. Table 1. Optimization of Reaction Conditionsa

entry catalyst

oxidant solvent T yield (3a, o b ( C) %) 1 Pd(OAc)2 air DCE 80 20 2 Pd(OAc)2 O2 DCE 80 25 3 Pd(OAc)2 O2 DCM 80 17 O2 THF 80 10 4 Pd(OAc)2 5 Pd(OAc)2 O2 MeCN 80 28 6 Pd(OAc)2 O2 DMSO 80 35 7 Pd(OAc)2 O2 DMF 80 43 c 8 Pd(OAc)2 BQ DMF 80 82 c 9 Pd(OAc)2 MBQ DMF 80 87 c 10 Pd(OAc)2 DMBQ DMF 80 60 c 11 Pd(OAc)2 DTBBQ DMF 80 63 c 12 Pd(OAc)2 MBQ DMF 100 43 c 13 Pd(OAc)2 MBQ DMF 60 ND c 14 Pd(OPiv)2 MBQ DMF 80 87 c 15 Pd(TFA)2 MBQ DMF 80 28 c 16 (MeCN)4Pd(OTf)2 MBQ DMF 80 20 c,d 17 Pd(OAc)2 MBQ DMF 80 87 c,d,e 18 Pd(OAc)2 MBQ DMF 80 8o c,d,f 19 Pd(OAc)2 MBQ DMF 80 63 c,d,g 20 Pd(OAc)2 MBQ DMF 80 ND a Reaction conditions: 1a (0.1 mmol), 2a (0.2 mmol), catalyst (0.01 mmol), oxidant (0.2 mmol), solvent (1 mL), 13 h. b 1 Determined by H NMR using CH2Br2 as the internal c d standard. Under Ar. Pd(OAc)2 (0.005 mmol) was used. e f MBQ (0.15 mmol) was used. MBQ (0.1 mmol) was used. g Ph2IOTf (0.1 mmol) instead of 2a. BQ = benzoquinone, MBQ = 2-methylbenzoquinone, DMBQ = 2,6-dimethyl-1,4benzoquinone, DTBBQ = 2,6-di-tert-butyl-1,4-benzoquinone.

For the initial studies, homoallylic amine (1a) and aryl iodide (2a) were chosen as model substrates (Table 1). In the presence of Pd(OAc)2 (10 mol %) at 80 oC in DCE under air, the desired product (3a) was isolated in 20% yield (entry 1). Single-crystal X-ray diffraction analysis of product 3a confirmed the structure (see Supporting Information). When the reaction was performed under O2 (1 atm), the yield of 3a increased only slightly to 25% (entry 2). The solvent effect was tested next (entries 3-7), and DMF was found to be the best solvent, affording 3a in

43% yield (entry 7). Oxidants were found to be essential in completing the annulation step. Of all the common oxidants including K2S2O8, DDQ, PhI(OAc)2, Ag2O, Cu(OAc)2, and BQ derivatives that were tested (entries 811), MBQ appeared to be most efficient (entry 9). Next, we screened the impact of temperature and found that the yield was negatively affected by either increasing or decreasing the reaction temperature (entries 12 and 13). Finally, we tested various palladium catalysts (entries 14-16), and Pd(OAc)2 was found to be the most suitable, even when the catalyst loading was reduced to 5 mol % (entry 17). Notably, Pd(PPh3)4 and Pd(dba)2 could not promote the reaction to form product 3a. Furthermore, decreasing the loading of MBQ led to slightly lower yield of 3a (entries 18 and 19). Control experiments using Ph2IOTf instead of 2a did not give the desired product 3a (entry 20). Under the optimized reaction conditions, the scope of the cascade reaction of homoallylic amines with aryl iodides was investigated (Scheme 2). First, different homoallylic amines were tested using 2a as a coupling partner. Homoallylic amines with different electrondonating groups, such as Me and MeO, underwent the cascade reaction to afford the corresponding products 3b and 3c in good yields. Furthermore, halogen-substituted amines and fluorine-substituted amine were also suitable substrates and gave the desired products 3d-g in moderate yields. To our delight, the unsymmetric aryl substituted amines also underwent the cascade reaction to form products 3h-l in moderate to good yields. Scheme 2. Substrate Scope of Cascade C−H Arylation/Aminationa

a

Reaction conditions: 1a (0.2 mmol), 2a (0.4 mmol), o Pd(OAc)2 (0.01 mmol), MBQ (0.4 mmol), DMF (2 mL), 80 C, under Ar. Isolated yields are noted.

However, the dialkyl substituted homoallylic amine failed to form the desired product 3m, similar to the monosubstituted homoallylic amines such as 1-phenylbut3-en-1-amine and 1-cyclohexylbut-3-en-1-amine. The results suggest that a suitable Thorpe-Ingold assistance is necessary for the amine substrates. A homoallylic amine

ACS Paragon Plus Environment

Page 2 of 7

Page 3 of 7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Catalysis with a methyl substituent at the aliphatic chain gave the desired product 3n in a moderate yield. Next, we evaluated the scope of aryl iodides. Iodobenzenes with different electron-donating groups at the para-position underwent the cascade reaction to afford the corresponding products 3o-q in moderate to good yields. Halogen-containing iodobenzenes at the para-position were found to be suitable substrates as well, generating products 3r-t in moderate yields. However, when iodobenzenes with strong electron-withdrawing groups, such as CF3, CN, or NO2, were used, no product was obtained. Similarly, no product was observed when the reaction was performed with aryl bromides or alkyl iodides. The meta-substituted iodobenzenes gave the products 3u-w in 55-70% yields. To our delight, ortho-substituted iodobenzenes could also give the desired product 3x in 70% yield, suggesting that the steric demands in aryl iodides are low for cascade reaction. Given the importance of heterocyclic compounds in the pharmaceutical industry, 2-iodothiophene was tested as the substrate, giving the desired product 3y in a moderate yield. Scheme 3. Transformation of 2-Aryl-1-pyrroline

To demonstrate the synthetic utility of the imines that were obtained in the cascade reaction, we performed the transformation of the 2-aryl-1-pyrroline 3a (Scheme 3). Specifically, the 3a was readily converted to 5-(4methoxyphenyl)-2,2-diphenylpyrrolidine (4, 86%) and 2butyl-2-(4-methoxyphenyl)-5,5-diphenylpyrrolidine (5, 71%) by two different nucleophilic additions. Scheme 4. Mechanistic Studies

was not essential for the formation of 6. For the reaction of 6 in the absence of MBQ, product 3a was not detected while diarylation product 7 was isolated in 46% yield (eq 2). These results, combined with the facts that the reaction of 1a and 2a could also afford the product 3a in the presence of O2 or BQ (Table 1, entries 7 and 8), demonstrated that MBQ played a role as an oxidant in the formation of 3a from 6. This notion was further supported by the detection of 2-methylbenzene-1,4-diol in the reaction mixture of eq 2 using GC-MS, as the product of MBQ. In the absence of 2a, the reaction of 6 could not produce product 3a (eq 2), but the similar reaction with catalytic amount of 2a (5 mol %) could afford the product 3a in 28% yield. In addition, more than 70% of 2a could be recovered with 12% yield of diarylation product 7 in the reaction of 6 under standard conditions (eq 2). These results indicated that the aryl iodide was not only an arylation reagent in the C−H arylation, but also played a pivotal role as a cocatalyst in the C−H amination of the cascade reaction. To further clarify the role of aryl iodides in the C−H amination, various halogen derivatives were tested for the intramolecular reaction with 6 (see SI). Interestingly, iodobenzene and 4-trifluoromethyl-iodobenzene also underwent the intramolecular reaction, giving 3a in 67% and 64% yields, respectively. In contrast, alkyl iodides and aryl bromides failed to yield any imines. Scheme 5. C−H Amination of Arylated Homoallylic Aminesa

a

Reaction conditions: 8 (0.1 mmol), 2a (0.1 mmol), Pd(OAc)2 o (0.005 mmol), MBQ (0.2 mmol), DMF (1 mL), 80 C, under Ar. Isolated yields are noted.

To clarify the mechanism of this cascade reaction, we tried to isolate the reaction intermediate by decreasing the reaction time to 0.5 h. As shown in Scheme 4, arylation product 6 was isolated, regardless of whether MBQ was used or not (eq 1). Moreover, the intramolecular reaction of 6 gave 3a in 73% yield under the standard conditions (eq 2). These results indicated that 6 was the key intermediate in the formation of product 3a and MBQ

In addition, the prepared intermediates 8 could convert to the desired products 3z and 3aa-3ac in 51-76% isolated yields with 2a as the cocatalyst (Scheme 5), although the direct reaction of the corresponding aryl iodides with 1a could not give the desired products. Interestingly, the stronger oxidant PhI(OAc)2 could also promote the intramolecular reaction to afford the desired product 3a in 60% isolated yield, even in the absence of MBQ (eq 3). This result indicates that aryl iodide and MBQ play a similar role with PhI(OAc)2 in the C–H amination, suggesting the catalytic cycle of [PdII] to [PdIV] might be involved.16 To further clarify the mechanism of the aryl iodidecocatalyzed C–H amination, we attempted to detect the reaction intermediates using ESI-HRMS. Specifically, when 6 reacted under the standard conditions with 2a for 6 h with or without MBQ, palladium intermediates C and E were detected (C: calcd for C46H45N2O2Pd+ [M+H]+: 763.2510, found: 763.2608, E: calcd for C53H51N2O3Pd+ [M+H]+: 869.2929, found: 869.3007, experimental isotopic distribution of two species matched the theoretical iso-

ACS Paragon Plus Environment

ACS Catalysis 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

topic distribution, see SI). The results suggest that the conversion of C to E does not involve MBQ and aryl iodides might act as the cocatalyst to promote the C−N formation in the C−H amination step. When 2a was replaced by diarylation product 7 in the reaction of 6, no product 3a could be detected (eq 4), although the palladium species with the same molecular weight of E can be detected in the reaction mixture. This result illustrates that the byproduct 7 could not act as a ligand to promote the C−H amination. On the basis of our mechanistic studies as well as previous literature reports,6b,c,16 a tentative mechanism for the cascade C−H arylation/amination of homoallylic amines with aryl iodides has been proposed (Scheme 6). First, Heck-coupling between aryl iodide 2 and the alkenyl moiety of homoallylic amine 1 in the presence of [PdII] occurs to generate the intermediate A.17 Then, A undergoes an amino-directed C−H activation with [PdII] to form alkene palladium intermediate C, which undergoes an oxidative addition with 2 to produce palladium intermediate E.18 The active aryl palladium catalyst G is generated from E and it undergoes oxidative C−H activation with A in the presence of MBQ to regenerate intermediate E, while MBQ is reduced to 2-methylbenzene-1,4diol. Then, the step from E to G will give the product 3 via tautomerization of F to complete the catalytic cycle. Scheme 6. Proposed Mechanism

In summary, we have developed a novel palladiumcatalyzed cascade C−H arylation/amination of homoallylic amines that provides concise access to 2-aryl1-pyrrolines with excellent regioselectivity and in good yields. Mechanistic investigations demonstrated that the reaction began with the coupling of aryl iodide to the C– H bond of terminal alkene, and the subsequent intramolecular C–H amination was promoted by the aryl iodide to generate a cyclic enamine intermediate, which underwent tautomerization to form the 2-pyrrolyl cyclic imine as the final product. The key roles of the aryl iodide were determined as an arylation reagent, as well as a cocatalyst to promote the C–N formation. This strategy allowed for the construction of C–N bonds by taking full advantage of the dual role of the aryl iodides, thus potentially providing novel opportunities for the synthesis of relevant useful molecules in the future.

ASSOCIATED CONTENT

This material is available free of charge via the Internet at http://pubs.acs.org. Experimental procedures, characterization data and spectra of products(PDF)，X-ray crystal structures of 3a (CIF)

AUTHOR INFORMATION Corresponding Author *[email protected]

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENT This research was supported by the National Natural Science Foundation of China (Project Nos. 21602059, 21421004, 21672059 and 21561162003), the Eastern Scholar Distinguished Professor Program, the China postdoctoral science foundation (2016T90341) and the Programme of Introducing Talents of Discipline to Universities (B16017).

REFERENCES (1) (a) Louillat, M. L.; Patureau, F. W. Oxidative C–H amination reactions. Chem. Soc. Rev. 2014, 43, 901−910. (b) Jeffrey, J. L.; Sarpong, R. Intramolecular C(sp3)–H amination. Chem. Sci. 2013, 4, 4092−4106. (c) Ramirez, T. A.; Zhao, B.; Shi, Y. Recent advances in transition metal-catalyzed sp3 C–H amination adjacent to double bonds and carbonyl groups. Chem. Soc. Rev. 2012, 41, 931−942. (2) (a) Hofmann, A. W. Ueber die Einwirkung des Broms in alkalischer Lösung auf die Amine. Ber. Dtsch. Chem. Ges. 1883, 16, 558−560. (b) Hofmann, A. W. Zur Kenntniss der ConiinGruppe. Ber. Dtsch. Chem. Ges. 1885, 18, 5−23. (c) Smith, A. C.; Williams, R. M. Rabe Rest in Peace: Confirmation of the Rabe– Kindler Conversion of d-Quinotoxine Into Quinine: Experimental Affirmation of the Woodward–Doering Formal Total Synthesis of Quinine. Angew. Chem., Int. Ed. 2008, 47, 1736−1740. (d) Qin, Q.; Yu, S. Visible-Light-Promoted Remote C(sp3)–H Amidation and Chlorination. Org. Lett. 2015, 17, 1894−1897. (e) Martínez, C.; Muñiz, K. An Iodine-Catalyzed Hofmann–Löffler Reaction. Angew. Chem., Int. Ed. 2015, 54, 8287−8291. (3) (a) Gruver, J. M.; West, S. P.; Collum, D. B.; Sarpong, R. Experimental Characterization and Computational Study of Unique C,N-Chelated Lithium Dianions. J. Am. Chem. Soc. 2010, 132, 13212−13213. (b) West, S. P.; Bisai, A.; Lim, A. D.; Narayan, R. R.; Sarpong, R. Total Synthesis of (+)-Lyconadin A and Related Compounds via Oxidative C−N Bond Formation. J. Am. Chem. Soc. 2009, 131, 11187−11194. (c) Bisai, A.; West, S. P.; Sarpong, R. Unified Strategy for the Synthesis of the “Miscellaneous” Lycopodium Alkaloids: Total Synthesis of (±)-Lyconadin A. J. Am. Chem. Soc. 2008, 130, 7222−7223. (4) (a) Xiong, T.; Zhang, Q. New amination strategies based on nitrogen-centered radical chemistry. Chem. Soc. Rev. 2016, 45, 3069−3087. (b) Roizen, J. L.; Harvey, M. E.; Du Bois, J. MetalCatalyzed Nitrogen-Atom Transfer Methods for the Oxidation of Aliphatic C–H Bonds. Acc. Chem. Res. 2012, 45, 911−922. (c) Davies, H. M. L.; Manning, J. R. Catalytic C–H functionalization by metal carbenoid and nitrenoid insertion. Nature 2008, 451, 417−424. (d) Paradine, S. M.; Griffin, J. R.; Zhao, J.; Petronico, A. L.; Miller, S. M.; White, M. C. A manganese catalyst for highly reactive yet chemoselective intramolecular C(sp3)–H amination. Nat. Chem. 2015, 7, 987−994. (e) Prier, C. K.; Zhang, R. K.; Buller, A. R.; Brinkmann-Chen, S.; Arnold, F. H. Enantioselective, intermolecular benzylic C–H amination catalysed by an engineered iron-haem enzyme. Nat. Chem. 2017, 9, 629−634. (f) Paudyal, M. P.; Adebesin, A. M.; Burt, S. R; Ess, D. H.; Ma, Z.;

ACS Paragon Plus Environment

Page 4 of 7

Page 5 of 7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Catalysis Kürti, L.; Falck, J. R. Dirhodium-catalyzed C–H arene amination using hydroxylamines. Science 2016, 353, 1144−1147. (5) (a) Park, Y.; Kim, Y.; Chang, S. Transition Metal-Catalyzed C–H Amination: Scope, Mechanism, and Applications. Chem. Rev. 2017, 117, 9247−9301. (b) Kim, H. Chang, S. The Use of Ammonia as an Ultimate Amino Source in the Transition MetalCatalyzed C–H Amination. Acc. Chem. Res. 2017, 50, 482−486. (c) Shin, K.; Kim, H.; Chang, S. Transition-Metal-Catalyzed C–N Bond Forming Reactions Using Organic Azides as the Nitrogen Source: A Journey for the Mild and Versatile C–H Amination. Acc. Chem. Res. 2015, 48, 1040−1052. (d) Yu, R.; Li, D.; Zeng, F. Palladium-Catalyzed Sequential Vinylic C–H Arylation/Amination of 2-Vinylanilines with Aryl boronic Acids: Access to 2-Arylindoles. J. Org. Chem. 2018, 83, 323−329. (e) Zhao, J.; Zhao, X.-J.; Cao, P.; Liu, J.-K.; Wu, B. Polycyclic Azetidines and Pyrrolidines via Palladium-Catalyzed Intramolecular Amination of Unactivated C(sp3)–H Bonds. Org. Lett. 2017, 19, 4880−4883. (f) Yamamoto, C.; Takamatsu, K.; Hirano, K.; Miura, M. A Divergent Approach to Indoles and Oxazoles from Enamides by Directing-Group-Controlled Cu-Catalyzed Intramolecular C–H Amination and Alkoxylation. J. Org. Chem. 2017, 82, 9112−9118. (g) Liu, L.; Qian, L.-W.; Wu, S.; Dong, J.; Xu, Q.; Zhou, Y.; Yin, S.F. Selective Aerobic C–H Amination of Phenols with Primary Amines over Copper toward Benzoxazoles. Org. Lett. 2017, 19, 2849−2852. (h) Yang, M.-Y.; Jiang, X.-Y.; Shi, Z.-J. Direct amidation of the phenylalanine moiety in short peptides via Pdcatalyzed C–H activation/C–N formation. Org. Chem. Front. 2015, 2, 51−54. (i) Neumann, J. J.; Rakshit, S.; Dröge, T.; Glorius, F. Palladium-Catalyzed Amidation of Unactivated C(sp3)–H Bonds: from Anilines to Indolines. Angew. Chem., Int. Ed. 2009, 48, 6892−6895. (j) Rice, G. T.; White, M. C. Allylic C−H Amination for the Preparation of syn-1,3-Amino Alcohol Motifs. J. Am. Chem. Soc. 2009, 131, 11707−11711. (k) Brasche, G.; Buchwald, S. L. C–H Functionalization/C–N Bond Formation: Copper-Catalyzed Synthesis of Benzimidazoles from Amidines. Angew. Chem., Int. Ed. 2008, 47, 1932−1934. (l) Leung, S. K.-Y.; Tsui, W.-M.; Huang, J.-S.; Che, C.-M.; Liang, J.-L.; Zhu, N. Imido Transfer from Bis(imido)ruthenium(VI) Porphyrins to Hydrocarbons:  Effect of Imido Substituents, C−H Bond Dissociation Energies, and RuVI/V Reduction Potentials. J. Am. Chem. Soc. 2005, 127, 16629−16640. (m) Espino, C. G.; Fiori, K. W.; Kim, M.; Du Bois, J. Expanding the Scope of C−H Amination through Catalyst Design. J. Am. Chem. Soc. 2004, 126, 15378−15379. (n) Liang, J.-L.; Yuan, S.-X.; Huang, J.-S.; Yu, W.-Y.; Che, C.-M. Highly Diastereo- and Enantioselective Intramolecular Amidation of Saturated C–H Bonds Catalyzed by Ruthenium Porphyrins. Angew. Chem., Int. Ed. 2002, 41, 3465−3468. (o) Liang, J.-L.; Huang, J.-S.; Yu, X.-Q.; Zhu, N.; Che, C.-M. Metalloporphyrin-Mediated Asymmetric Nitrogen-Atom Transfer to Hydrocarbons: Aziridination of Alkenes and Amidation of Saturated C−H Bonds Catalyzed by Chiral Ruthenium and Manganese Porphyrins. Chem. -Eur. J. 2002, 8, 1563−1572. (p) Guthikonda, K.; Du Bois, J. A Unique and Highly Efficient Method for Catalytic Olefin Aziridination. J. Am. Chem. Soc. 2002, 124, 13672−13673. (q) Espino, C. G.; Du Bois, J. A RhCatalyzed C−H Insertion Reaction for the Oxidative Conversion of Carbamates to Oxazolidinones. Angew. Chem., Int. Ed. 2001, 40, 598−600. (6) (a) Wu, X.; Yang, K.; Zhao, Y.; Sun, H.; Li, G.; Ge, H. Cobalt-catalysed site-selective intra- and intermolecular dehydrogenative amination of unactivated sp3 carbons. Nat. Commun. 2015, 6, 6462−6471. (b) Mei, T.-S.; Wang, X.; Yu, J.-Q. Pd(II)Catalyzed Amination of C−H Bonds Using Single-Electron or Two-electron Oxidants. J. Am. Chem. Soc. 2009, 131, 10806−10807. (c) Wasa, M.; Yu, J.-Q. Synthesis of β-, γ-, and δLactams via Pd(II)-Catalyzed C−H Activation Reactions. J. Am. Chem. Soc. 2008, 130, 14058−14059. (d) Inamoto, K.; Saito, T.; Katsuno, M.; Sakamoto, T.; Hiroya, K. Palladium-Catalyzed C−H

Activation/Intramolecular Amination Reaction: A New Route to 3-Aryl/Alkylindazoles. Org. Lett. 2007, 9, 2931−2934. (e) Tsang, W. C. P.; Zheng, N.; Buchwald, S. L. Combined C−H Functionalization/C−N Bond Formation Route to Carbazoles. J. Am. Chem. Soc. 2005, 127, 14560−14561. (7) (a) Wappes, E. A.; Fosu, S. C.; Chopko, T. C.; Nagib, D. A. Triiodide-Mediated δ-Amination of Secondary C−H Bonds. Angew. Chem., Int. Ed. 2016, 55, 9974−9978. (b) Yang, M.; Su, B.; Wang, Y.; Chen, K.; Jiang, X.; Zhang, Y.-F.; Zhang, X.-S.; Chen, G.; Cheng, Y.; Cao, Z.; Guo, Q.-Y.; Wang, L.; Shi, Z.-J. Silvercatalysed direct amination of unactivated C−H bonds of functionalized molecules. Nat. Commun. 2014, 5, 4707−4712. (c) He, G.; Zhang, S.-Y.; Nack, W. A.; Li, Q.; Chen, G. Use of a Readily Removable Auxiliary Group for the Synthesis of Pyrrolidones by the Palladium-Catalyzed Intramolecular Amination of Unactivated γ C(sp3)−H Bonds. Angew. Chem., Int. Ed. 2013, 52, 11124−11128. (d) He, G.; Zhao, Y.; Zhang, S.; Chen, G. Highly Efficient Syntheses of Azetidines, Pyrrolidines, and Indolines via Palladium Catalyzed Intramolecular Amination of C(sp3)–H and C(sp2)–H Bonds at γ and δ Positions. J. Am. Chem. Soc. 2012, 134, 3−6. (e) Nadre, E. T.; Daugulis, O. Heterocycle Synthesis via Direct C–H/N–H Coupling. J. Am. Chem. Soc. 2012, 134, 7−10. (f) Li, J.-J.; Mei, T.-S.; Yu, J.-Q. Synthesis of Indolines and Tetrahydroisoquinolines from Arylethylamines by PdII-Catalyzed C–H Activation Reactions. Angew. Chem., Int. Ed. 2008, 47, 6452−6455. (8) Thu, H.-Y.; Yu, W.-Y.; Che, C.-M. Intermolecular Amidation of Unactivated sp2 and sp3 C−H Bonds via PalladiumCatalyzed Cascade C−H Activation/Nitrene Insertion. J. Am. Chem. Soc. 2006, 128, 9048−9049. (9) (a) Wu, H.; He, Y.-P.; Xu, L.; Zhang, D.-Y.; Gong, L.-Z. Asymmetric Organocatalytic Direct C(sp2)–H/C(sp3)–H Oxidative Cross-Coupling by Chiral Iodine Reagents. Angew. Chem., Int. Ed. 2014, 53, 3466−3469. (b) Ito, M.; Kubo, H.; Itani, I.; Morimoto, K.; Dohi, T.; Kita, Y. Organocatalytic C–H/C–H’ Cross-Biaryl Coupling: C-Selective Arylation of Sulfonanilides with Aromatic Hydrocarbons. J. Am. Chem. Soc. 2013, 135, 14078−14081. (c) Dohi, T.; Minamitsuji, Y.; Maruyama, A.; Hirose, S.; Kita, Y. A New H2O2/Acid Anhydride System for the Iodoarene-Catalyzed C−C Bond-Forming Reactions of Phenols. Org. Lett. 2008, 10, 3559−3562. (10) (a) Wang, X.; Gallardo-Donaire, J.; Martin, R. Mild ArICatalyzed C(sp2)–H or C(sp3)–H Functionalization/C–O Formation: An Intriguing Catalyst-Controlled Selectivity Switch. Angew. Chem., Int. Ed. 2014, 53, 11084−11087. (b) Dohi, T.; Kita, Y. New Site-Selective Organoradical Based on Hypervalent Iodine Reagent for Controlled Alkane sp3 C–H Oxidations. ChemCatChem. 2014, 6, 76−78. (c) Dohi, T.; Takenaga, N.; Nakae, T.; Toyoda, Y.; Yamasaki, M.; Shiro, M.; Fujioka, H.; Maruyama, A.; Kita, Y. Asymmetric Dearomatizing Spirolactonization of Naphthols Catalyzed by Spirobiindane-Based Chiral Hypervalent Iodine Species. J. Am. Chem. Soc. 2013, 135, 4558−4566. (d) Dohi, T.; Maruyama, A.; Takenaga, N.; Senami, K.; Minamitsuji, Y.; Fujioka, H.; Caemmerer, S. B. A Chiral Hypervalent Iodine(III) Reagent for Enantioselective Dearomatization of Phenols. Angew. Chem., Int. Ed. 2008, 47, 3787−3790. (e) Ochiai, M.; Takeuchi, Y.; Katayama, T.; Sueda, T.; Miyamoto, K. Iodobenzene-Catalyzed α-Acetoxylation of Ketones. In Situ Generation of Hypervalent (Diacyloxyiodo)benzenes Using m-Chloroperbenzoic Acid. J. Am. Chem. Soc. 2005, 127, 12244−12245. (11) (a) Wappes, E. A.; Nakafuku, K. M.; Nagib, D. A. Directed β C–H Amination of Alcohols via Radical Relay Chaperones. J. Am. Chem. Soc. 2017, 139, 10204−10207. (b) Manna, S.; Matcha, K.; Antonchick, A. P. Metal-Free Annulation of Arenes with 2Aminopyridine Derivatives: The Methyl Group as a Traceless Non-Chelating Directing Group. Angew. Chem., Int. Ed. 2014, 53, 8163−8166. (c) Manna, S.; Antonchick, A. P. Organocatalytic Oxidative Annulation of Benzamide Derivatives with Alkynes.

ACS Paragon Plus Environment

ACS Catalysis 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Angew. Chem., Int. Ed. 2014, 53, 7324−7327. (d) Alla, S. K.; Kumar, R. K.; Sadhu, P.; Punniyamurthy, T. Iodobenzene Catalyzed C–H Amination of N-Substituted Amidines Using mChloroperbenzoic Acid. Org. Lett. 2013, 15, 1334−1337. (e) Samanta, R.; Lategahn, J.; Antonchick, A. P. Metal-free direct oxidative intermolecular diarylation of anilides at ambient temperature assisted by cascade selective formation of C–C and C–N bonds. Chem. Commun. 2012, 48, 3194−3196. (12) (a) Dohi, T.; Takenage, N.; Fukushima, K.; Uchiyama, T.; Kato, D.; Motoo, S.; Fujioka, H.; Kita, Y. Designer μ-oxo-bridged hypervalent iodine(III) organocatalysts for greener oxidations. Chem. Commun. 2010, 46, 7697−7699. (b) Dohi, T.; Maruyama, A.; Minamitsuji, Y.; Takenaga, N.; Kita, Y. First hypervalent iodine(III)-catalyzed C–N bond forming reaction: catalytic spirocyclization of amides to N-fused spirolactams. Chem. Commun. 2007, 1224−1226. (c) Wappes, E. A.; Fosu, S. C.; Chopko, T. C.; Nagib, D. A. Triiodide-Mediated δ-Amination of Secondary C−H Bonds. Angew. Chem., Int. Ed. 2016, 55, 9974−9978. (d) Zhu, C.; Liang, Y.; Hong, X.; Sun, H.; Sun, W.-Y.; Houk, K. N.; Shi, Z. Iodoarene-Catalyzed Stereospecific Intramolecular sp3 C–H Amination: Reaction Development and Mechanistic Insights. J. Am. Chem. Soc. 2015, 137, 7564−7567. (e) Antonchick, A. P.; Samanta, R.; Kulikov, K.; Lategahn, J. Organocatalytic, Oxidative, Intramolecular C–H Bond Amination and Metal-free Cross-Amination of Unactivated Arenes at Ambient Temperature. Angew. Chem., Int. Ed. 2011, 50, 8605−8608. (13) (a) Bonney, K. J.; Schoenebeck, F. Experiment and computation: a combined approach to study the reactivity of palladium complexes in oxidation states 0 to IV. Chem. Soc. Rev. 2014, 43, 6609−6638. (14) (a) Race, N. J.; Faulkner, A.; Fumagalli, G.; Yamauchi, T.; Scott, J. S.; Rydén-Landergren, M.; Sparkes, H. A.; Bower, J. F. Enantioselective Narasaka–Heck cyclizations: synthesis of tetrasubstituted nitrogen-bearing stereocenters. Chem. Sci. 2017, 8, 1981–1985. (b) Yang, H.-B; Pathipati, S. R.; Selander, N. NickelCatalyzed 1,2-Aminoarylation of Oxime Ester-Tethered Alkenes with Boronic Acids. ACS Catal. 2017, 7, 8441−8445. (c) Jiang, H.; Studer, A. Iminyl-Radicals by Oxidation of α-Imino-oxy Acids: Photoredox-Neutral Alkene Carboimination for the Synthesis of Pyrrolines. Angew. Chem., Int. Ed. 2017, 56, 12273–12276. (d) Kondo, T.; Okada, T.; Mitsudo, T. Ruthenium-Catalyzed Intramolecular Oxidative Amination of Aminoalkenes Enables Rapid Synthesis of Cyclic Imines. J. Am. Chem. Soc. 2002, 124, 186–187. (e) Pugin, B.; Venanzi, L. M. Palladium-Catalyzed Oxidation of Amino Alkenes to Cyclic Imines or Enamines and Amino Ketones. J. Am. Chem. Soc. 1983, 105, 6877–6881.

(15) (a) Li, D. Y.; Chen, H. J.; Liu, P. N. Tunable Cascade Reactions of Alkynols with Alkynes under Combined Sc(OTf)3 and Rhodium Catalysis. Angew. Chem., Int. Ed. 2016, 55, 373−377. (b) Li, D. Y.; Jiang, L. L.; Chen, S.; Huang, Z. L.; Dang, L.; Wu, X. Y.; Liu, P. N. Cascade Reaction of Alkynols and 7Oxabenzonorbornadienes Involving Transient Hemiketal Group Directed C–H Activation and Synergistic RhIII/ScIII Catalysis. Org. Lett. 2016, 18, 5134−5137. (c) Shang, X. S.; Li, N. T.; Li, D. Y.; Liu, P. N. Palladium-Catalyzed Tandem Reaction of AlkyneBased Aryl Iodides and Salicyl N-Tosylhydrazones to Construct the Spiro[benzofuran-3,2’-chromene] Skeleton. Adv. Synth. Catal. 2016, 358, 1577−1582. (d) Liu, K.; Chen, S.; Li, X. G.; Liu, P. N. Multicomponent Cascade Synthesis of Trifluoroethyl Isoquinolines from Alkynes and Vinyl Azides. J. Org. Chem. 2016, 81, 265−270. (16) (a) Hickman, A. J.; Sandord, M. S. High-valent organometallic copper and palladium in catalysis. Nature 2012, 484, 177−185. (b) McNally, A.; Haffemayer, B.; Collins, B. S. L.; Gaunt, M. J. Palladium-catalysed C−H activation of aliphatic amines to give strained nitrogen heterocycles. Nature 2014, 510, 129−133. (c) He, G.; Lu, G.; Guo, Z.; Liu, P.; Chen, G. Benzazetidine synthesis via palladium-catalysed intramolecular C−H amination. Nat. Chem. 2016, 8, 1131−1136. (d) Jordan-Hore, J. A.; Johansson, C. C. C.; Gulias, M.; Beck, E. M.; Gaunt, M. J. Oxidative Pd(II)Catalyzed C−H Bond Amination to Carbazole at Ambient Temperature. J. Am. Chem. Soc. 2008, 130, 16184−16186. (e) Furuya, T.; Ritter, T. Carbon−Fluorine Reductive Elimination from a HighValent Palladium Fluoride. J. Am. Chem. Soc. 2008, 130, 10060−10061. (f) Whitfield, S. R.; Sanford, M. S. Reactivity of Pd(II) Complexes with Electrophilic Chlorinating Reagents:  Isolation of Pd(IV) Products and Observation of C−Cl BondForming Reductive Elimination. J. Am. Chem. Soc. 2007, 129, 15142−15143. (17) Yao, Q.; Kinney, E. P.; Yang, Z. Ligand-Free Heck Reaction:  Pd(OAc)2 as an Active Catalyst Revisited. J. Org. Chem. 2003, 68, 7528−7531. (18) (a) Sehnal, P.; Taylor, R. J. K.; Fairlamb, I. J. S. Emergence of Palladium(IV) Chemistry in Synthsis and Catalysis. Chem. Rev. 2010, 110, 824−889. (b) Xu, L.-M.; Li, B.-J.; Yang, Z.; Shi, Z.-J. Organopalladium(IV) chemistry. Chem. Soc. Rev. 2010, 39, 712−733. (c) Zhu, R.-Y.; Li, Z.-Q.; Park, H. S.; Senanayake, C. H.; Yu, J.-Q. Ligand-Enabled γ‑C(sp3)−H Activation of Ketones. J. Am. Chem. Soc. 2018, 140, 3564−3568.

ACS Paragon Plus Environment

Page 6 of 7

Page 7 of 7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Catalysis

Table of Contents Graphic

ACS Paragon Plus Environment

7