Generation and Suppression of 3-/4-Functionalized Benzynes Using Zinc Ate Base (TMP−Zn−ate):  New Approaches to Multisubstituted Benzenes

Uchiyama, Masanobu; Kobayashi, Yuri; Furuyama, Taniyuki; Nakamura, Shinji; Kajihara, Yumiko; Miyoshi, Tomoko; Sakamoto, Takao; Kondo, Yoshinori; Morokuma, Keiji

doi:10.1021/ja071268u

Cited by 130 publications

(51 citation statements)

References 22 publications

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“…Thus, the stability of the Ni(0)-ate complex appears to be mainly determined by the σ-donation ability of the organometallic nucleophiles R- [M]. In our previous reports, we have found that in organozincates [77][78][79][80][81][82][83][84][85] the anionic character of C-Zn bond could be drastically enhanced (Table 1 85) ). …”

Section: Resultsmentioning

confidence: 99%

Ethereal C–O Bond Cleavage Mediated by Ni(0)-Ate Complex: A DFT Study

et al. 2017

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Density functional theory calculations were performed to explore the mechanism of Ni-catalyzed crosscoupling reactions involving organo-lithium and -zinc reagents through ethereal C-O bond cleavage. Based on this work, together with our previous mechanistic study on etheric Kumada-Tamao reaction, we identify and characterize a novel catalytic cycle for cross-coupling mediated by Ni(0)-ate complex.Key words cross-coupling; ether; nickel catalyst; organolithium; organozinc; density functional theory (DFT) calculation Efficient and selective cleavage and transformation of C-O bonds, particularly by means of cross-coupling methods, has attracted great interest, since compounds containing C-O moieties occur widely in nature and are also extensively utilized in industry.1-8) Among C-O compounds, ethers are particularly attractive, [1][2][3][4][5][6][7][8] as they offer the advantages of 1) high atom economy/conversion efficiency (the use of ethers as simple as MeO as substrates affords fewer by-products compared with tosylate, mesylate, triflate, phosphate, etc.), 2) environmental compatibility (cleavage of the C-O moiety in ether releases non-halogen-containing waste), and 3) excellent stability, easy accessibility and wide diversity. However, ethereal C-O bonds ( E C-O) are very unreactive, and most of the well-established Pd-catalyzed C-O bond-cleaving protocols are ineffective for ethers.On the other hand, Ni-catalysts have proved effective for many types of C-O bond cleavage, including ethers. As early as in 1979, Wenkert et al. 9,10) reported the first Ni-catalyzed Kumada-Tamao type (Mg) 9-23) reaction, in which aryl methyl ether (ArOMe) acted as the electrophilic partner, and this is now recognized as the first example of Ni-catalyzed activation of an inert C-O bond. However, this breakthrough was overlooked for decades, until quite recently. After the development of improved conditions, ArOR can now be used as a coupling partner in several types of transition metal (TM)-catalyzed cross-couplings and related transformations, such as Suzuki-Miyaura-type (B), [24][25][26][27][28][29][30][31] Negishi-type (Zn or Al), [32][33][34][35][36] Murahashi-type (Li), [37][38][39][40] and other reactions. 41-50) As a continuation of our work in this area, we reported in 2012 the first ethereal Negishi-type coupling of aryl alkyl ether 36) (Chart 1(1)) and in 2016 we reported a systematic examination of ethereal Murahashi-type reaction 37) (Chart 1(2)). More recently, we also reported an in-depth study of Ni-catalyzed cross-coupling between organoaluminums and various types of C-O electrophiles, including aryl alkyl ether. 32) Results and DiscussionThe conventional catalytic cycle for cross-coupling reaction consists of three elemental steps: oxidative addition (OA), transmetalation, and reductive elimination. [51][52][53][54] Martin and colleagues reported that direct OA of a E C-O bond to Ni(0) requires high temperature, based on experimental and theoretical findings.46) Computational studies by Nakamura and colleagues, ...

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Section: Resultsmentioning

confidence: 99%

Ethereal C–O Bond Cleavage Mediated by Ni(0)-Ate Complex: A DFT Study

et al. 2017

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“…Thus novel classes of metallating agents resulting from various combinations of organometallic compounds with alkali, including various ate complexes, have been designed, such as zincates (R 2 Zn(TMP)Li·TMEDA) [3–4] ((TMP) 2 Zn·2MgCl 2 ·2LiCl) [5], magnesates ((TMP) 3 MgLi, Bu 2 (TMP)MgLi, Bu(TMP) 2 MgLi, (TMP) 4 MgLi 2 ) [3,6], aluminates (iBu 3 Al(TMP)Li, Al(TMP) 3 ·3LiCl) [3,7], manganate ((Me 3 SiCH 2 ) 2 Mn(TMP)Li·TMEDA) [3,8], cuprates (MeCu(TMP)(CN)Li 2 , (TMP) 2 CuLi) [9–10] and cadmium amides ((TMP) 3 CdLi) [11–12], for regio- and/or chemoselective deprotonative metalation of aromatics, producing arylmetal intermediates under smooth reaction conditions that are directly suitable for electrophilic reactions as well as transition-metal-catalyzed cross-coupling reactions. By contrast, the methodology for transition-metal-catalyzed direct arylation [13–18] is based upon the use of various catalytic metalation processes, such as electrophilic metalation, oxidative addition, halogen- or base-assisted metalation–deprotonation, and carbometalation [19–22] combined with diverse functionalizing agents, such as alkenes and alkynes [23], oxidants [24], nucleophiles, organometallics and arenes [25–26] (Scheme 1).…”

Section: Introductionmentioning

confidence: 99%

Recent advances in direct C–H arylation: Methodology, selectivity and mechanism in oxazole series

Verrier¹,

Lassalas²,

Théveau³

et al. 2011

Beilstein J. Org. Chem.

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SummaryCatalytic direct (hetero)arylation of (hetero)arenes is an attractive alternative to traditional Kumada, Stille, Negishi and Suzuki–Miyaura cross-coupling reactions, notably as it avoids the prior preparation and isolation of (hetero)arylmetals. Developments of this methodology in the oxazole series are reviewed in this article. Methodologies, selectivity, mechanism and future aspects are presented.

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“…10 In order to seek more efficient and direct methods for introducing functionalities into heteroaromatic rings, we focused the deprotonative 65 metalation using the corresponding mixture with cadmium instead of zinc on the difference of metal size. First attempts using anisole (1a) as substrate indicated that an in situ prepared mixture of CdCl 2 ·TMEDA 11 (0.5 equiv) and LiTMP (1.5 equiv) was suitable for an efficient reaction, when used in 70 THF at room temperature.…”

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confidence: 99%