Ni(COD) - ACS Publications - American Chemical Society

Article Cite This: Organometallics XXXX, XXX, XXX−XXX

Ni(COD)2‑Catalyzed ipso-Silylation of 2‑Methoxynaphthalene: A Density Functional Theory Study Pooja Jain,† Sourav Pal,†,§ and Vidya Avasare*,‡ †

Department of Chemistry, Indian Institution of Technology Bombay, Mumbai 400076, India Department of Chemistry, Sir Parashurambhau College, Pune 411030, India

‡

S Supporting Information *

ABSTRACT: Density functional theory has been used for the systematic investigation of the mechanism involved in Ni(COD)2catalyzed ipso-silylation of 2-methoxynaphthalene. The two fundamental mechanistic pathways, internal nucleophilic substitution and a nonclassical oxidative addition, have been studied. In both pathways, the first equivalent of KOtBu directly reacts with the silyl boronate (Et3SiBpin) to generate the silyl anion surrogate Et3SiK or silylborate [Et3Si-Bpin(OtBu)]K (IN3), which further reacts with Ni(COD)2 to form a substrate−catalyst complex, [(η2-COD)2NiSiEt3]K. The internal nucleophilic substitution reaction pathway proceeds through η2 complexation of nickel with the C(1)C(2) bond of 2-methoxynaphthalene. Later, nickel connects to C(1) through σ-bond formation and coordinates with oxygen of the −OMe group. Simultaneously, the −SiEt3 group approaches C(2) possessing −OMe followed by rearomatization which is facilitated by coordination of K+ with nickel and methoxy oxygen. In a nonclassical oxidative addition, the chelation of K+ with −OMe as well as −SiEt3 from [(η2COD)2NiSiEt3] is the key step which promotes the insertion of NiSiEt3 to the C(2) carbon of 2-methoxynaphthalene. We also observed that the activation energy barrier in the non-π-extended aromatic systems is higher than that of the π-extended aromatic systems. The overall study manifests that Ni(COD)2-catalyzed ipso-silylation of 2-methoxynapthalene operates through an internal nucleophilic substitution pathway.

1. INTRODUCTION There has been a phenomenal growth in nickel-catalyzed reactions after the discovery of Ni(COD)2 by Wilke.1 In general, nickel catalysts have attracted wide attention in recent years due to their appealing catalytic behavior, cost effectiveness, and easy availability. Organometallic nickel complexes containing Ni−C bonds exhibit air and moisture sensitivity; however, their excellent catalytic performance makes them worthy in transition-metal catalysis.2,3 They have shown promising applications in cross-coupling, C−H activation, olefin oligomerization, and cycloaddition reactions.4−12 In spite of their low cost, easy synthesis, and air and moisture stability, the higher C(sp2)−OMe (C−OMe) bond energy of aryl ethers has restricted their applications in transition-metalcatalyzed organic transformations.13−16 Most of the C−OMe activation reactions require expensive low-valent transitionmetal catalysts, expensive ligands, excessive addition of ligands, and elevated temperatures.17 Interestingly, nickel catalysts have been found to be effective in the transformation of the less reactive C−OMe bond of aryl ethers into C−C, C− heteroatom, and C−Si cross-coupling reactions under milder reaction conditions.18 The C−OMe activation reactions © XXXX American Chemical Society

provide robust as well as practical solutions for the synthesis of organic compounds, pharmaceuticals, and industrially important intermediates on a large scale.19 The synthesis of novel organosilanes has provided important precursors in the synthesis of aromatic sulfones, natural products, and nanomaterials.20−25 Therefore, the synthesis of a C−Si bond through C−OMe activation has become a notable area of research. Although there have been many reports on mechanistic investigations of transition-metal-catalyzed reactions, there have been few mechanistic studies on nickel-catalyzed activation of aryl ethers.22−30 All these mechanistic studies of C−OMe bond activation suggest that the nature of the nucleophile, substrate, and type of base used in the reactions are the key components to determine the mechanistic pathways. In 2017, Martin and co-workers developed a facile reaction protocol for aryl silylation through C−OMe bond activation (Scheme 1).31 Martin’s silylation protocol does not require the use of additives or excess addition of ligands, and it works even at ambient temperature to Received: January 23, 2018

A

DOI: 10.1021/acs.organomet.8b00046 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics

addition with the π-extended aromatic systems. Here, we found that internal nucleophilic substitution reaction is preferred over the nonclassical oxidative addition pathway. In these computational studies, the nickel from the [(η2COD)2NiSiEt3]K complex first forms a η2-π-complex with an activated aromatic ring, in particular the C(1)C(2) bond possessing an −OMe group, and then it attaches to C(1) through σ-bond and the oxygen of the −OMe group coordinates with nickel. Simultaneously, the −SiEt3 group approaches C(2); thus, internal nucleophilic substitution takes place with the elimination of the −OMe group.37 Apart from its significant role in the generation of a highly reactive [(η2-COD)2NiSiEt3]K complex and stabilization of Bpin(OtBu)2K, K+ also facilitates the removal of −OMe in the internal nucleophilic substitution reaction. KOtBu promotes the cleavage of the B−Si bond in silyl boronate (Et3SiBpin) and enhances the nucleophilicity of −SiEt3. It also stabilizes the Lewis acid, Bpin-OtBu by forming the stable Bpin(OtBu)2K. Therefore, further interference of Bpin-OtBu can be avoided by adding a second equivalent of KOtBu to the reaction. In a nonclassical oxidative addition, the chelation of K+ with −OMe as well as −SiEt3 is observed. In short, the cleavage of the C−O bond proceeds through either internal nucleophilic substitution (path A) or direct nonclassical oxidative addition (path B) (Scheme 3). The present study endorses the experimental findings that the π-extended aromatic systems, in particular 2-methoxynaphthalene, exhibit better reactivities and yields in comparison to anisoles, including activated anisoles. Here, we have employed

Scheme 1. ipso-Silylation of 2-Methoxynaphthalene31

produce aryltrialkylsilylanes from 2-methoxynaphthalene in a reasonably short reaction time. The economical, environmentally benign, and novel protocol developed by Martin and co-workers for ipso-silylation through C−OMe bond activation has attracted our attention. According to the experimental observations, π-extended aryl ethers or anisoles with electronrich groups at the ortho/para position give better yields in comparison to regular anisole derivatives.32−36 Although plausible mechanistic pathways were proposed by Martin, detailed mechanistic investigations have not been carried out. Therefore, we probed the plausible mechanistic steps involved in the ipso-silylation of 2-methoxynaphthalene through C− OMe bond activation on the basis of Martin’s experimental results. Recently, Fu and co-workers have also reported the mechanism of formation of aryl silyl ethers using Martin’s protocol.37 The reaction mechanisms suggested by Fu’s group and our group have completely different approaches, and our mechanistic investigations provide a lower energy barrier (Scheme 2). We have employed higher levels of the functional and different basis sets for the geometry optimization. Fu and his co-workers investigated the mechanism on the basis of oxidative addition for the non-π-extended aromatic systems, while we studied two different mechanistic pathways involving internal nucleophilic substitution and nonclassical oxidative Scheme 2. Mechanistic Investigations of ipso-Silylation

B


Article

Organometallics Scheme 3. Plausible Pathways for the ipso-Silylation through C−O Bond Activation in 2-Methoxynaphthalene

using AIM2000 software with the wave function generated at the CPCM(toluene)/M06/LANL2DZ(Ni),6-31G** level of theory.57−60 This analysis was employed to identify weak interatomic interactions within a given transition-state structure.

density functional theory in order to understand the nature of the potential active species, key intermediates, and transition states involved in the reaction. The reported mechanism can be useful for the further advancement of Ni-catalyzed carbon− heteroatom bond activation reactions in aromatics and nonaromatics.

3. RESULTS AND DISCUSSION 3.1. Formation of [Et3Si-Bpin(OtBu)]K, Silyl Anion Surrogate. The Ni(COD)2-catalyzed silylation in the presence of 2.2 equiv of KOtBu was found to give better yields at ambient temperature (Scheme 1).31 The first mole of KOtBu directly reacts with the silyl boronate (Et3SiBpin) to generate Et3SiK or the silylborate [Et3Si-Bpin(OtBu)]K (IN3), which acts as a silyl anion surrogate (Scheme 4)31 The attack of the

2. COMPUTATIONAL DETAILS Computational studies were performed using the Gaussian09 suite of quantum chemical programs.38 The geometries were first optimized using M06 density functional theory.39 The M06 functional has been extensively used in recent literature to account well for noncovalent interactions in transition-metal systems, thermochemistry, barrier heights, and weak interactions as implemented in Gaussian 09.40−45 The Pople 6-31G** basis set was used for all atoms except Ni.40−44 The LANL2DZ and ECP (augmented with one f function, Ni(ζf) = 3.130) basis set consisting of an effective core potential (ECP) and a double-ζ quality valence basis set for two valence electrons was used for nickel and other metals.45−47 All of the stationary points were characterized, as minima or a first-order saddle point (transition states).48 The transition states were verified by acquiring a unique imaginary frequency. Calculations of intrinsic reaction coordinates (IRC) were also performed on transition states to confirm that such structures are indeed connecting two minima.49−51 The solvation correction was performed by using the conductor-like polarizable continuum model (CPCM).52 Single-point energies were calculated at the CPCMtoluene/M06/6-31G**,LANL2DZ(Ni) levels of theory using the M06/6-31G**,LANL2DZ(Ni) geometries.52 The zero-point vibrational energy (ZPVE), thermal, and entropic corrections obtained at 298.15 K and 1 atm pressure borrowed from the gas-phase computations at the M06/6-31G**,LANL2DZ(Ni) levels of theory have been enforced to the “bottom-of-the-well” energies obtained from the single-point energy evaluations in the solvent phase at the M06 functional to assess the Gibbs free energies of solutes in the condensed phase.53 The energy span was calculated using the energetic span model developed by Shaik and Kozuch that expresses the turnover frequency (TOF) of a catalytic cycle using the energetics of various stationary points such as the turnover-determining intermediate (TDI) and transition state (TDTS).54−56 The energetic span of the cycle δE can be calculated as

Scheme 4. Mechanistic Path for the Formation of Catalyst− Substrate Complex

−OtBu anion on the Lewis acid Et3Si-Bpin remains the driving force for the formation of Et3SiK or silylborate [Et3SiBpin(OtBu)]K (IN3). IN3 further reacts with Ni(COD)2 and forms an active catalyst−substrate complex (IN4), which was used in both pathways, A and B. The second mole of KOtBu facilitates the formation of the active catalyst complex [(η2-COD)2NiSiEt3]K (IN4) through the stabilization of the Lewis acid by formation of [BPin(OtBu)2]K. The base interacts with silyl boronate (Et3SiBpin) to generate IN1 with a free energy of −0.7 kcal/mol, and then IN1 converts into the silylborane intermediate IN2 via the transition state TS[1-2] (Figure 1). The oxygen of the OtBu− donates a pair of electrons to an empty p orbital of the electron-deficient boron, resulting in a lowering of the activation energy barrier by 0.5 kcal/mol for TS[1-2] with respect to IN1. Similar findings have been reported for the activation of silyl boranes by other Lewis bases

δE = TTDTS − ITDI if the TDTS is after the TDI and δE = TTDTS − ITDI + ΔGrx if the TDTS is before the TDI (where ΔGrx is the Gibbs free energy of the reaction). Topological analysis of the electron density distribution was performed using Bader’s atoms in molecules (AIM) formalism by C


Article

Organometallics

Figure 1. Gibbs free energy (kcal/mol) profile at the CPCM/M06/6-31G**/LANL2DZ(Ni)//M06/6-31G**/LANL2DZ(Ni) level of theory for the formation of catalyst−substrate complex.

(H2O or OH−) in Cu(II)-catalyzed silyl conjugate addition to α,β-unsaturated carbonyl compounds in the presence of an aqueous amine.61,62 The intermediate IN3 is obtained from IN2 through the transition state TS[2-3] with an energy barrier of 3.5 kcal/mol. In the transition state TS[2-3], the cleavage of the B−Si bond results in the formation of a new Si−K bond (IN3).This IN3 is slightly exergonic with −2.6 kcal/mol free energy. In IN3, the −SiEt3 moiety is successfully delivered to the potassium site in a concerted manner. Throughout the mechanism, KSiEt3 is an active species which finally adds to Ni0(COD)2 and dissociation of the Bpin-OtBu from IN3 leads to the formation of nickel−silyl complex IN4. The free energy increases by 4.3 kcal/mol from IN3 to IN4. Thus, the negatively charged Ni center (Mulliken charge −0.84) and the positively charged Si atom (Mulliken charge 0.370) interact electrostatically in IN4 (Figure 2). The formation of IN4 is in agreement with a discrete [Ni(COD)SiEt3]K complex reported by Martin and co-workers.31 3.2. Path A: Internal Nucleophilic Aromatic Substitution via Aromatic Backbone. In path A, the internal nucleophilic aromatic substitution is assisted by complexation of the K+ counterion with the lone pair of the ethereal oxygen atom (Figure 3). This step is initiated from IN4 with a free

energy of 1.7 kcal/mol as previously depicted (Scheme 4). Later, 2-methoxynaphthalene adds to IN4 and generates the intermediate IN5 with a free energy of 11.8 kcal/mol. The free energy change during the association of IN4 and 2methoxynapthalene is 10.1 kcal/mol. The strong Ni−Si interaction is endorsed by the shorter Ni−Si bond length (2.3 Å). Mulliken atomic charges on the nickel (−1.37) and silicon (1.29) also support the strong electrostatic attraction between nickel and silicon atoms in the Ni(0)-ate complex IN5, and no critical points are observed. The longer Ni−K bond distance (4.5 Å) in intermediate IN5 supports that potassium ion acts as a counterion and does not interact with nickel. The Ni(0)-ate complex formed in IN5 is consistent with the single-crystal X-ray structure reported by Pörschke and co-workers.63 In IN5, [Ni(η2-COD)SiEt3]K shows η2 coordination with a double bond of an activated aromatic ring of 2-methoxynaphthalene. Since the η 4 coordination complex of nickel lacks a vacant coordinate site for further reaction, nickel forms a η2 coordination complex to facilitate further reaction. The intermediate complex IN5 leads to the formation of IN6 through the transition state TS[5-6]. In the transition state TS[5-6], the Ni−Si bond cleavage is assisted by transfer of the π-bond density of the C(1)C(2) to the d orbital of nickel. In the transition state TS[5-6], the silyl anion attack is clearly indicated by the changes in bond distances between Ni−Si (2.3 Å) and Si−C(2) (3.8 Å) in IN5 to 3.7 and 1.92 Å in TS[5-6], respectively. Thus, transition state TS[5-6] nicely depicts the approach of −SiEt3 to C(2), to which −OMe is attached through the changes in the bond distances as shown in Figure 4. Here, the Ni−Si bond distance changes from 2.3 Å (IN5) to 3.7 Å (IN6) and, similarly, the Si−C(2) bond distance changes from 3.8 Å (IN5) to 1.9 Å (IN6) (Figure 4). In short, the transition state TS[5-6] describes the entire mechanism of formation of Si−C(2) (1.9 Å), Ni−C(1) (2.8 Å), and Ni−O (2.6 Å) bonds and also shows the weakening/loss of interactions between Ni and Si (3.7 Å). The free energy barrier of this nucleophilic aromatic substitution step is 22.9 kcal/mol, which is in agreement with the reported activation energy barrier (21 kcal/mol) of other transition-metal-catalyzed nucleophilic aromatic substitution reactions.64 The distance between potassium and oxygen (2.41 Å) is shorter than the Ni−K distance (3.26 Å), which implies stronger K−O and not Ni−K interactions. The change in the bond distance endorses the involvement of K+ in this reaction through complexation

Figure 2. Optimized geometry and Mulliken charge of the intermediate [(η2-COD)2NiSiEt3]K (IN4). D


Article

Organometallics

Figure 3. Gibbs free energy (kcal/mol) profile at the CPCM/M06/6-31G**/LANL2DZ(Ni)//M06/6-31G**/LANL2DZ(Ni) level of theory for path A.

Figure 4. Optimized geometries of IN5, TS[5-6], and IN6.

The AIM analysis for the transition state TS[5-6] indicates the strong noncovalent interactions between different hydrogen atoms. Thus, all of the above factors contribute to a feasible internal nucleophilic aromatic substitution through the ratedetermining step TS[5-6].The transition state TS[5-6] further proceeds to the formation of IN6 with a loss of aromaticity. In

with a lone pair of the methoxy oxygen atom. Due to the ring constraint the nickel does not bind to cyclooctadiene (COD) ligand in the same fashion as for Ni(η4-COD)2; therefore, η2 coordination of COD with nickel occurs in the transition state TS[5-6]. E


Article

Organometallics

Figure 5. Optimized geometries of TS[6-7] and IN7.

Scheme 5. Catalytic Cycle of the Internal Nucleophilic Substitution Reaction (Path A)

becomes activated. In TS[6-7], K+ attracts the −OMe group, expedites the cleavage of the C(2)−OMe bond, and forms the strong K−OMe bond (2.5 Å) (Figure 5).The loss of −OMe from TS[6-7] retains the aromaticity in the intermediate IN7 with a lowering of an exergonic free energy value to −33.7 kcal/ mol. Here, the methoxy oxygen also coordinates to nickel through the donation of a pair of electrons to an empty d orbital of nickel, which results in IN7 with a tetrahedral geometry. The shorter Ni−OMe bond distance (1.86 Å) is indicative of the formation of a Ni−O bond in IN7. In this complex, nickel partially interacts with the π density of the 2methoxynaphthalene ring; this is a highly exergonic step. After the formation of IN7, release of product P and formation of the intermediate K(η4-COD)NiOMe (IN8) occur. The lower free

intermediate IN6, the Ni(0) and the methoxy group are coordinated with a free energy of 1.4 kcal/mol, which further facilitates the departure of −OMe from C(2). However, the naphthalene ring facilitates η2 coordination to a low-valent nickel complex and it also helps to retain the partial aromaticity. In C−OMe functionalization, π-extended aromatic systems exhibit better reaction rates than the regular anisole derivatives. The results obtained here are in good agreement with C− OMe functionalization literature reports.14,17,32 3.2.1. Potassium Ion Assisted Aromaticity Retention. The intermediate IN6 formed after the internal nucleophilic aromatic substitution becomes less stable due to the loss of aromaticity. IN6 further proceeds to give the concerted fourmembered transition state TS[6-7], in which the C−O bond F


Article

Organometallics

Figure 6. Gibbs free energy (kcal/mol) profile at the CPCM/M06/6-31G**/LANL2DZ(Ni)//M06/6-31G**/LANL2DZ(Ni) level of theory for path B.

energy of IN8 (−45.5 kcal/mol) in comparison to K(η2COD)NiOMe (−44.4 kcal/mol) confirms η4 coordination of the COD ligand with nickel. The COD ligand, which is released from [(η2-COD)2NiSiEt3]K (IN4) during the formation of IN5, adds to IN8 to give IN9 with a free energy of −52.7 kcal/ mol. The removal of KOMe from IN9 regenerates the catalyst Ni(COD)2with a free energy of −54.9 kcal/mol. In IN3, KSiEt3 is formed in the resting state, and the actual internal nucleophilic aromatic substitution is the rate-determining step, TS[5-6]. The complete catalytic cycle is consistent with the experimental results (Scheme 5). Overall, the reaction is exergonic by 54.9 kcal/mol with a suitable barrier of 22.9 kcal/ mol at the rate-determining step, TS[5-6] (Figure 3). 3.3. Path B: Nonclassical Oxidative Addition. Path B has also been initiated from IN4 (Scheme 4). The intermediate IN10 forms through the coordination of IN4 with 2methoxynaphthalene with a loss of one COD ligand (Figure 6). The Ni−Si bond from intermediate IN5 becomes weak, and potassium ion bridging becomes significant between −OMe and −SiEt3 in IN10. Thus, K+ acts as a Lewis acid to activate the C−OMe bond cleavage. In IN10, the association complex of both reactants increases the free energy to 13.6 kcal/mol. IN10 also shows the coordination of Ni(0) to the π plane of naphthyl, and KSiEt3 forms a Lewis acid−base complex with the methoxy oxygen. Path B has a slightly lower activation energy barrier in comparison to the normal classical oxidative addition via a three-membered transition state.65 The migration of the −SiEt3 group to the Ni(0) center takes place easily to generate the “Ni(0)-ate complex” (IN11) through the transition state TS[10-11] with an activation energy barrier of 29.7 kcal/mol. The cleavage of the C−OMe bond takes place smoothly for IN12 through the five-

membered rate-determining transition state TS[11-12], having a high activation energy barrier of 31.7 kcal/mol. The release of −OMe from the transition state TS[11-12] leads to the formation of IN13 with a lowering of the free energy to −13.2 kcal/mol. Finally, the product IN14 forms through the reductive elimination of Ni(COD)2 complex from TS[13-14] with a very low activation energy barrier of 3.3 kcal/mol. In short, we have investigated two fundamental mechanistic pathways, path A and path B, representing internal nucleophilic aromatic substitution through an aromatic backbone and a nonclassical oxidative addition, respectively. During our detailed mechanistic investigations, we found that the ratedetermining step of path A, TS[5-6] (22.9 kcal/mol), has a lower activation energy barrier in comparison to the ratedetermining step of path B, TS[11-12] (35 kcal/mol). Therefore, we suggest that path A is the most preferred mechanistic pathway. This study encouraged us to probe into the silylation of non-π-extended derivatives using the principles of the internal nucleophilic aromatic substitution via an aromatic backbone (path A). 3.4. Silylation of Non-π-Extended Derivatives. According to the experimental study, C−OMe functionalization of πextended aromatic systems provides consistently higher yields in comparison to regular anisole derivatives.31 Toward this point, we studied some of the representative examples of anisoles to understand the effect of π-extended aromatic systems on the rate-determining step of path A (Figure 3). The unsubstituted anisole IN5a (Scheme 6) is formed with −0.61 kcal/mol free energy. IN5a undergoes internal nucleophilic aromatic substitution to give IN6a through TSa[5-6], but the activation energy barrier of this TSa[5-6] (41.9 kcal/mol) is G


Organometallics

■

Scheme 6. Silylation of Non-π-Extended Derivativesa

Article

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.8b00046. Energetic span calculations, detailed AIM analysis, summary of electron densities at the bond critical points, topological maps, optimized geometries of important intermediates, and transition states of path B (PDF) Optimized Cartesian coordinates of all species involved (XYZ)

■ a

AUTHOR INFORMATION

Corresponding Author

*E-mail for V.A.: [email protected].

Free energy values are given in kcal/mol.

ORCID

Sourav Pal: 0000-0002-4836-639X Vidya Avasare: 0000-0002-6428-591X

much higher than that for TS[5-6] (22.9 kcal/mol) of πextended aromatic systems. The ability of π-extended aromatic systems for η 2 coordination with nickel and retention of the aromaticity of at least one of the naphthalene rings are attributed to the lowering of activation energy in TS[5-6] (22.9 kcal/mol). In the case of non-π-extended aromatic systems, weak η 2 coordination with nickel and a loss of aromaticity results in a high activation energy barrier in TSa[5-6] (41.9 kcal/mol). The study of anisole with ortho/para activating groups reveals a further lowering of the activation energy barrier (36.5 kcal/ mol) of TSb[5-6] in comparison to TSa[5-6]. Thus, an increase in the electron density of activated anisoles strengthens η2 coordination with nickel and results in a lowering of activation energy of TSb[5-6] by 5.4 kcal/mol in comparison to TSa[5-6]. In short, ortho/para activated anisoles give better yields in comparison to unsubstituted anisoles. However, the activation energy barrier still remains high in the non-πextended aromatic systems in comparison to π-extended aromatic systems.

Present Address

§ Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, Naida, West Bengal, India.

Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS P.J. and S.P. acknowledge the J. C. Bose Fellowship grant of the DST. V.A. thanks the CSIR for funding under extramural grants. The authors acknowledge Bangaru Bhaskararao and Rahul Shukla for useful discussions. We also thank the IIT Bombay Computer Centre facility.

■

REFERENCES

(1) Wilke, G. Angew. Chem., Int. Ed. Engl. 1988, 27, 185−206. (2) Zarate, C.; Van Gemmeren, M.; Somerville, R. J.; Martin, R. Adv. Organomet. Chem. 2016, 66, 143−222. (3) Tollefson, E. J.; Hanna, L. E.; Jarvo, E. R. Acc. Chem. Res. 2015, 48, 2344−2353. (4) Tsou, T. T.; Kochi, J. K. J. Am. Chem. Soc. 1979, 101, 6319−6332. (5) Sengupta, S.; Leite, M.; Raslan, D. S.; Quesnelle, C.; Snieckus, V. J. Org. Chem. 1992, 57, 4066−4068. (6) Garcia, J. J.; Brunkan, N. M.; Jones, W. D. J. Am. Chem. Soc. 2002, 124, 9547−9555. (7) Tobisu, M.; Xu, T.; Shimasaki, T.; Chatani, N. J. Am. Chem. Soc. 2011, 133, 19505−19511. (8) (a) O’Connor, C. T.; Kojima, M. Catal. Today 1990, 6, 329−349. (b) Ge, S.; Hartwig, J. F. Angew. Chem., Int. Ed. 2012, 51, 12837− 12841. (9) Tao, J.-Y.; Fang, D.-C.; Chass, G. A. Phys. Chem. Chem. Phys. 2012, 14, 6937−6945. (10) Yamaguchi, J.; Muto, K.; Itami, K. Eur. J. Org. Chem. 2013, 2013, 19−30. (11) Tasker, S. Z.; Standley, E. A.; Jamison, T. F. Nature 2014, 509, 299−309. (12) Omer, H. M.; Liu, P. J. Am. Chem. Soc. 2017, 139, 9909−9920. (13) Meijere, A. D.; Diederich, F. O. Metal Catalysed Cross-Coupling Reactions, 2nd ed.; Wiley-VCH: Weinheim, Germany, 2004. (14) Handbook of Organopalladium Chemistry for Organic Synthesis; Negishi, E.-i., de Meijere, A., Eds.; Wiley-Interscience: New York, 2002. (15) Wenkert, E.; Michelotti, E. L.; Swindell, C. S. J. Am. Chem. Soc. 1979, 101, 2246−2247. (16) Li, B.-J.; Yu, D.-G.; Sun, C.-L.; Shi, Z.-J. Chem. - Eur. J. 2011, 17, 1728−1759.

4. CONCLUSION A density functional theory study of Ni(COD)2-catalyzed ipsosilylation of 2-methoxynaphthalene reveals that the internal nucleophilic aromatic substitution reaction mechanism (path A) is assisted by the complexation of nickel, [(η 2 COD)2NiSiEt3]K, with a lone pair of methoxy oxygen. This Ni and −OMe coordination facilitates the detachment of the C(2)−OMe bond and further assists the insertion of −SiEt3 to C(2). Path A is exergonic by −54.9 kcal/mol with a suitable energy barrier of 22.9 kcal/mol at the rate-determining step TS[5-6]. Path B demonstrated nonclassical oxidative addition (path B) with a higher activation energy barrier (35 kcal/mol) in its rate-determining step TS[11-12], making it less feasible than path A. The stronger η2 coordination of nickel in activated anisole slows the energy barrier by 5.0 kcal/mol in comparison to nonactivated anisoles. However, the activation energy barrier still remains high in the activated anisoles in comparison to π-extended aromatic systems. The ipso-silylation of 2-methoxynapththalene through C−OMe activation proceeds through an internal nucleophilic substitution pathway, which is more facile and feasible than a normal or a nonclassical oxidative addition. These results should provide a precedent for understanding nickel-catalyzed C−heteroatom bond activation reactions with further modifications at wider scales. H


Article

Organometallics (17) (a) Zarate, C.; Manzano, R.; Martin, R. J. Am. Chem. Soc. 2015, 137, 6754−6757. (b) Tobisu, M.; Yasutome, A.; Yamakawa, K.; Shimasaki, T.; Chatani, N. Tetrahedron 2012, 68, 5157−5161. (c) Tobisu, M.; Shimasaki, T.; Chatani, N. Chem. Lett. 2009, 38, 710−711. (18) (a) Rosen, B. M.; Quasdorf, K. W.; Wilson, D. A.; Zhang, N.; Resmerita, A.; Garg, N. K.; Percec, V. Chem. Rev. 2011, 111, 1346− 1416. (b) Martin, S. E. S.; Watson, D. A. J. Am. Chem. Soc. 2013, 135, 13330−13333. (19) (a) Nicolaou, K. C.; Bulger, P. G.; Sarlah, D. Angew. Chem., Int. Ed. 2005, 44, 4442−4489. (b) Corbet, J.-P.; Mignani, G. Chem. Rev. 2006, 106, 2651−2710. (20) Von Wolff, N.; Char, J.; Frogneux, X.; Cantat, T. Angew. Chem., Int. Ed. 2017, 56, 5616−5619. (21) Díez-Poza, C.; Barbero, A. Eur. J. Org. Chem. 2017, 2017, 4651− 4665. (22) Wu, L.; Zhang, J. P.; Li, B. C.; Wang, A. Q. J. Mater. Chem. B 2013, 1, 4756−4763. (23) Zhang, J. P.; Li, B. C.; Wu, L.; Wang, A. Q. Chem. Commun. 2013, 49, 11509−11511. (24) Zhang, J. P.; Wang, A. Q.; Seeger, S. Polym. Chem. 2014, 5, 1132−1139. (25) Cornella, J.; Gómez-Bengoa, E.; Martin, R. J. Am. Chem. Soc. 2013, 135, 1997−2009. (26) Ogawa, H.; Minami, H.; Ozaki, T.; Komagawa, S.; Wang, C.; Uchiyama, M. Chem. - Eur. J. 2015, 21, 13904−13908. (27) Sergeev, A. G.; Hartwig, J. F. Science 2011, 332, 439−443. (28) Sawatlon, B.; Wititsuwannakul, T.; Tantirungrotechai, Y.; Surawatanawong, P. Dalton Trans. 2014, 43, 18123−18133. (29) Xu, L.; Chung, L. W.; Wu, Y.-D. ACS Catal. 2016, 6, 483−493. (30) Schwarzer, C. M.; Konno, R.; Hojo, T.; Ohtsuki, A.; Nakamura, K.; Yasutome, A.; Takahashi, H.; Shimasaki, T.; Tobisu, M.; Chatani, N.; Mori, S. J. Am. Chem. Soc. 2017, 139, 10347−10358. (31) Zarate, C.; Masaki, N.; Martin, R. J. Am. Chem. Soc. 2017, 139, 1191−1197. (32) (a) Tobisu, M.; Chatani, N. Acc. Chem. Res. 2015, 48, 1717− 1726. (b) Cornella, J.; Zarate, C.; Martin, R. Chem. Soc. Rev. 2014, 43, 8081−8097. (33) (a) Guo, L.; Liu, X.; Baumann, C.; Rueping, M. Angew. Chem., Int. Ed. 2016, 55, 15415−15419. (b) Zhao, Y.; Snieckus, V. J. Am. Chem. Soc. 2014, 136, 11224−11227. (34) Yu, D.-G.; Shi, Z.-J. Angew. Chem., Int. Ed. 2011, 50, 7097−7100. (35) Yu, D. G.; Li, B. J.; Zheng, S. F.; Guan, B. T.; Wang, B. Q.; Shi, Z. J. Angew. Chem., Int. Ed. 2010, 49, 4566−4570. (36) Alvarez-Bercedo, R.; Martin, R. J. Am. Chem. Soc. 2010, 132, 17352−17353. (37) Wang, B.; Zhang, Q.; Jiang, J.; Yu, H.; Fu, Y. Chem. - Eur. J. 2017, 23, 17249−17256. (38) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery, J. A., Jr.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, revision C.01; Gaussian Inc., Wallingford, CT, 2010. (39) Zhao, Y.; Schultz, N. E.; Truhlar, D. G. Theor. Chem. Acc. 2008, 120, 215−241. (40) Liu, P.; Xu, X.; Dong, X.; Keitz, B. K.; Herbert, M. B.; Grubbs, R. H.; Houk, K. N. J. Am. Chem. Soc. 2012, 134, 1464−1467.

(41) (a) Komagawa, S.; Wang, C.; Morokuma, K.; Saito, S.; Uchiyama, M. J. Am. Chem. Soc. 2013, 135, 14508−14511. (b) Wang, Z. J.; Benitez, D.; Tkatchouk, E.; Goddard, W. A.; Toste, F. D. J. Am. Chem. Soc. 2010, 132, 13064−13071. (42) Biswas, S.; Huang, Z.; Choliy, Y.; Wang, D. Y.; Brookhart, M.; Krogh-Jespersen, K.; Goldman, A. S. J. Am. Chem. Soc. 2012, 134, 13276−13295. (43) (a) Zhao, Y.; Truhlar, D. G. Acc. Chem. Res. 2008, 41, 157−167. (b) Minenkov, Y.; Occhipinti, G.; Jensen, V. R. J. Phys. Chem. A 2009, 113, 11833−11844. (44) Pratt, L. M.; Voit, S.; Okeke, F. N.; Kambe, N. J. Phys. Chem. A 2011, 115, 2281−2290. (45) (a) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Chem. Phys. 1972, 56, 2257−2261. (b) Hariharan, P. C.; Pople, J. A. Theor. Chim. Acta 1973, 28, 213−222. (c) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B: Condens. Matter Mater. Phys. 1988, 37, 785−789. (d) Becke, A. D. J. Chem. Phys. 1993, 98, 5648−5652. (46) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 299−310. (47) (a) Ehlers, A. W.; Bohme, M.; Dapprich, S.; Gobbi, A.; Hollwarth, A.; Jonas, V.; Kohler, K. F.; Stegmann, R.; Veldkamp, A.; Frenking, G. Chem. Phys. Lett. 1993, 208, 111−114. (b) Bhattacharjee, R.; Nijamudheen, A.; Karmakar, S.; Datta, A. Inorg. Chem. 2016, 55, 3023−3029. (c) Bhattacharjee, R.; Nijamudheen, A.; Datta, A. Org. Biomol. Chem. 2015, 13, 7412−7420. (48) (a) Gonzalez, C.; Schlegel, H. B. J. Chem. Phys. 1989, 90, 2154. (b) Gonzalez, C.; Schlegel, H. B. J. Phys. Chem. 1990, 94, 5523−5527. (49) (a) Fukui, K. J. Phys. Chem. 1970, 74, 4161−4163. (b) Fukui, K. Acc. Chem. Res. 1981, 14, 363−368. (50) Hratchian, H. P.; Schlegel, H. B. J. Chem. Phys. 2004, 120, 9918−9924. (51) Hratchian, H. P.; Schlegel, H. B. J. Chem. Theory Comput. 2005, 1, 61−69. (52) (a) Miertuš, S.; Scrocco, E.; Tomasi. Chem. Phys. 1981, 55, 117−129. (b) Tomasi, J.; Mennucci, B.; Cammi, R. Chem. Rev. 2005, 105, 2999−3098. (c) Scalmani, G.; Frisch, M. J. J. Chem. Phys. 2010, 132, 114110−114124. (53) Jindal, G.; Sunoj, R. B. J. Am. Chem. Soc. 2014, 136, 15998− 16008. (54) Kozuch, S. WIREs Comput. Mol. Sci. 2012, 2, 795−815. (55) See Table S1 in the Supporting Information for a compilation of various possible ways to determine the maximum δE for the catalytic cycle. (56) Kozuch, S.; Lee, S. E.; Shaik, S. Organometallics 2009, 28, 1303− 1308. (57) AIM2000 version 2.0; Buro fur Innovative Software, SBK Software, Bielefeld, Germany, 2002. (58) Bader, R. F. W. Chem. Rev. 1991, 91, 893−928. (59) Biegler-Konig, F.; Schonbohm, J.; Bayles, D. J. Comput. Chem. 2001, 22, 545−559. (60) See Figure S1 in the Supporting Information for topological analysis of electron density using atoms in molecule analysis. (61) Kleeberg, C.; Borner, C. Eur. J. Inorg. Chem. 2013, 2013, 2799− 2806. (62) Calderone, J. A.; Santos, W. L. Org. Lett. 2012, 14, 2090−2093. (63) Jonas, K.; Pörschke, K. R.; Krüger, C.; Tsay, Y.-H. Angew. Chem., Int. Ed. Engl. 1976, 15, 621−622. (64) O’Reilly, M. E.; Johnson, S. L.; Nielsen, R. J.; Goddard, W. A.; Gunnoe, T. B. Organometallics 2016, 35, 2053−2056. (65) See the Supporting Information.

I


Ni(COD) - ACS Publications - American Chemical Society

Recommend Documents