Cross‐Coupling of Alkynylsilanols with Aryl Halides Promoted by Potassium Trimethylsilanolate.

Denmark, Scott E.; Tymonko, Steven A.

doi:10.1002/chin.200413065

Cited by 4 publications

(4 citation statements)

References 2 publications

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“…90,91 Additionally, the reaction conditions resemble those for the KOTMS-promoted Hiyama−Denmark crosscoupling reaction. 27 Actually, Denmark and Tymonko examined the KOTMS-promoted activation of the alkynyl TMS in the presence of a copper cocatalyst at ambient temperature, 27 and the similar result was observed in our reaction at 45 °C (entry 9). Although our approach employs a copper cocatalyst with thermal assistance to activate the alkynyl TMSs, we believe that the utility of the alkynyl TMSs as the organosilane species is practically straightforward to versatile synthetic approaches.…”

Section: ■ Results and Discussionsupporting

confidence: 79%

“…88,89 Denmark and Tymonko reported that potassium trimethylsilanolate (KOTMS) efficiently activates the alkynylsilanols in the Hiyama−Denmark cross-coupling reaction (Scheme 1E). 27 Encouraged by the report, we examined KOTMS as the silanolate instead of methanolate in the synthesis of 1 Ant and found that the KOTMS-promoted conditions drastically improved the yield of 1 Ant (75%) (entry 7). The result indicates the kinetic preference of the Sonogashira catalytic cycles under the KOTMS-promoted conditions.…”

Section: ■ Results and Discussionmentioning

confidence: 97%

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Trimethylsilanolate-Promoted Activation of Alkynyl Trimethylsilanes: Hiyama-Type Sonogashira Cross-Coupling for the Synthesis of Arylene–Ethynylene-Linked Porphyrin Arrays

et al. 2022

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To synthesize meso-ethynylene-conjugated porphyrin arrays, the Sonogashira cross-coupling reaction is straightforward to construct the C(sp)–C(sp2) bonds, but the reaction is often accompanied by side reactions such as the Glaser homocoupling. The rate-determining oxidative addition step results in the unexpected kinetic competition with the Glaser homocoupling, which is desired to be circumvented. We here propose two sets of improved strategies for the synthesis of arylene–ethynylene-linked porphyrin arrays from the meso-brominated porphyrin and alkynes. First, we explored the solvent-modulated approach employing dichloromethane as the reaction solvent to minimize the formation of the copper acetylide dimer as the intermediate for the Glaser homocoupling, while the scope of the approach is limited. Subsequently, we have developed the trimethylsilanolate-promoted Hiyama-type approach that activates alkynyl trimethylsilanes (TMSs) by use of potassium trimethylsilanolate under amine-free conditions. The latter approach is advantageous not only in skipping the preprotodesilylation of the TMS group but also in achieving an excellent isolated yield.

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Section: ■ Results and Discussionsupporting

confidence: 79%

Section: ■ Results and Discussionmentioning

confidence: 97%

Trimethylsilanolate-Promoted Activation of Alkynyl Trimethylsilanes: Hiyama-Type Sonogashira Cross-Coupling for the Synthesis of Arylene–Ethynylene-Linked Porphyrin Arrays

et al. 2022

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“…Initial studies revealed that dimethyl(1-heptynyl)silanol 14 is a much more effective coupling partner than 1-heptyne or (1-heptynyl)trimethylsilane under silanolate activation. 25 With 2.0 equiv of KOSiMe 3 , (Ph 3 P) 2 PdCl 2 , and CuI, the cross-coupling reaction of 14 with 4-iodoanisole is complete after 3 h, whereas 1-heptyne or (1-heptynyl)trimethyl silane affords <20% conversion. Clearly, KOSiMe 3 must activate the silanol without cleavage of the Si-C bond, because in situ deprotection would give identical rates for alkynes 14 and 1-heptyne.…”

Section: Kinetic Analysis and Mechanistic Implicationsmentioning

confidence: 99%

Palladium-Catalyzed Cross-Coupling Reactions of Organosilanols and Their Salts: Practical Alternatives to Boron- and Tin-Based Methods

2008

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ConspectusIn the panoply of modern synthetic methods for forming carbon-carbon and carbon-heteroatom bonds, the transition metal-catalyzed cross coupling of organometallic nucleophiles with organic electrophiles enjoys a preeminent status. The preparative utility of these reactions is, in large measure, a consequence of the wide variety of organometallic donors that have been conscripted into service. The most common of these reagents are organic derivatives of tin, boron, and zinc, which each possess unique advantages and shortcomings. Because of their low cost, low toxicity, and high chemical stability, organosilanes have emerged as viable alternatives to the conventional reagents in recent years. However, unlike the tin-and zinc-based reactions that require no activation or the boron-based reactions that require only heating with mild bases, silicon-based cross-coupling reactions often require heating in the presence of a fluoride source; this has significantly hampered the widespread acceptance of organosilanes.To address the "fluoride problem", we have introduced a new paradigm for palladium-catalyzed, silicon-based cross-coupling reactions that employs organosilanols, a previously underutilized class of silicon reagents. The use of organosilanols either in the presence of Brønsted bases or as their silanolate salts represents a simple and mild alternative to the classic fluoride-based activation method. Organosilanols are easily available by many well-established methods for introducing carbon-silicon bonds onto alkenes, alkynes and arenes, and heteroarenes. Moreover, we have developed four different protocols for the generation of alkali metal salts of, vinyl-, alkenyl-, alkynyl-, aryl-, and heteroarylsilanolates: (1) reversible deprotonation with weak Brønsted bases, (2) irreversible deprotonation with strong Brønsted bases, (3) isolation of the salts from irreversible deprotonation, and (4) silanolate exchange with disiloxanes. We have demonstrated the advantages of each of these methods for a number of different coupling classes.The defining feature of this new process is the formation of a covalently linked palladium silanolate species that facilitates the critical transmetalation step. We have verified the intermediacy of a critical species that contains the key Si-O-Pd linkage by its identification as the resting state in reaction mixtures, by X-ray analysis, and by demonstrating its competence in thermal cross-coupling with no * Address Correspondence to: Professor Scott E. Denmark, 245 Roger Adams Laboratory, Box 18, Department of Chemistry, University of Illinois, 600 S. Mathews Avenue, Urbana, IL 61801, phone: (217) 333-0066, fax: (217) 333-3984, email: denmark@scs.uiuc "...Work in this field (silicon-based cross-coupling) has been quite active since the initial disclosure of siletane cross-coupling from these laboratories... Future studies are focused on several fronts, including the extension of scope to incorporate less reactive substrates such as chlorides and triflates, further optimiza...

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“…10 As an organic base, TMSOK was also explored by Procopiou et al 11 to prepare E-alkenes by inducing the elimination of potassium arenesulfinates from alkyl aryl sulfones. More importantly, the Denmark group found that TMSOK greatly promoted the Sonogashira reaction 12 and the Suzuki−Miyaura reaction 13−16 under anhydrous conditions, reducing the reaction time by more than 10 times. The above examples show the considerable potential of TMSOK as a base to promote the homogeneous, anhydrous Suzuki−Miyaura cross-coupling.…”

Section: Introductionmentioning

confidence: 99%

Suzuki C–C Coupling in Paper Spray Ionization: Microsynthesis of Biaryls and High-Sensitivity MS Detection of Aryl Bromides

Lin

Xue

Sun

et al. 2022

J. Am. Soc. Mass Spectrom.

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Suzuki–Miyaura cross-coupling is one of the most powerful strategies for constructing biaryl compounds. However, classic Suzuki–Miyaura coupling suffers from hour-scale reaction time and competitive protodeboronation. To address these problems, a mild nonaqueous potassium trimethylsilanolate (TMSOK)-assisted Suzuki–Miyaura coupling strategy was designed for the microsynthesis of biaryls in paper spray ionization (PSI). Due to the acceleration power facilitated by microdroplet chemistry in reactive PSI, the microsynthesis of biaryls by reactive PSI was accomplished within minutes with comparable yields to the bulk, showing good substrate applicability from 32 Suzuki–Miyaura reactions of aryl bromides and aryl boronic acid/borates bearing different substituents. Based on the above TMSOK-assisted Suzuki–Miyaura coupling strategy, we further developed a high-sensitivity and selective PSI mass spectrometry (MS) method for quantitative analysis of aryl bromides, a class of environmentally persistent organic pollutants that cannot be directly detected by ambient mass spectrometry due to their low ionization efficiency. In situ derivatization of aryl bromides was achieved with aryl borates bearing quaternary ammonium groups in PSI. The proposed PSI-MS method shows good linearity over the 0.01–10 μmol L–1 range with low detection limits of 1.8–4.8 nmol L–1 as well as good applicability to the rapid determination of six aryl bromides in three environmental water samples. The proposed PSI-MS method also shows good applicability to brominated flame retardants (polybrominated diphenyls/diphenyl esters). Overall, this study provides a simple, rapid, low-cost, high-sensitivity, and high-selectivity strategy for trace aryl bromides and other brominated pollutants in real samples with minimal/no sample pretreatment.

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Cross‐Coupling of Alkynylsilanols with Aryl Halides Promoted by Potassium Trimethylsilanolate.

Cited by 4 publications

References 2 publications

Trimethylsilanolate-Promoted Activation of Alkynyl Trimethylsilanes: Hiyama-Type Sonogashira Cross-Coupling for the Synthesis of Arylene–Ethynylene-Linked Porphyrin Arrays

Trimethylsilanolate-Promoted Activation of Alkynyl Trimethylsilanes: Hiyama-Type Sonogashira Cross-Coupling for the Synthesis of Arylene–Ethynylene-Linked Porphyrin Arrays

Palladium-Catalyzed Cross-Coupling Reactions of Organosilanols and Their Salts: Practical Alternatives to Boron- and Tin-Based Methods

Suzuki C–C Coupling in Paper Spray Ionization: Microsynthesis of Biaryls and High-Sensitivity MS Detection of Aryl Bromides

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