Stereospecific Palladium-Catalyzed Cross-Coupling of (<i>E</i>)- and (<i>Z</i>)-Alkenylsilanolates with Aryl Chlorides

Denmark, Scott E.; Kallemeyn, Jeffrey M.

doi:10.1021/ja065988x

Cited by 80 publications

(46 citation statements)

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“…Whereas the lithium silanolate from LiOt-Bu can be formed as a stable species, this salt is less nucleophilic, and likely suffers from slow displacement of the palladium halide. 60 In contrast, when NaOt-Bu was used, the more nucleophilic and stable sodium silanolate gave modest yields (46%). The use of KOt-Bu proved less successful, and can be understood by the observed instability of the potassium silanolate.…”

Section: Optimization Of the Cross-coupling Reactionmentioning

confidence: 99%

“…60 A variety of substituted (E)-and (Z)-alkenylsilanolates underwent cross-coupling with substituted aryl chlorides in THF or dioxane in the presence of 2.5 mol % of [allylPdCl] 2 , and 5 mol %, of the substituted biphenyl-based ligand, S-Phos (38). 61 Initial optimization studies with Na + 13 − , 4-chloroanisole was selected as the electrophile.…”

Section: Optimization Of the Cross-coupling Of N-sem-dimethyl(2-indolmentioning

confidence: 99%

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Palladium-Catalyzed Cross-Coupling of Five-Membered Heterocyclic Silanolates

2008

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The preparation of π-rich 2-aryl heterocycles by palladium-catalyzed cross-coupling of sodium heteroarylsilanolates with aryl iodides, bromides and chlorides is described. The cross-coupling process was developed through extensive optimization of the follow key variables: (1) identification of stable, isolable alkali metal silanolates, (2) identification of conditions for preformation and isolation of silanolate salts, (3) judicious choice in the palladium catalyst/ligand combination, and (4) selection of the protecting group on the nitrogen of indole. It was found that the alkali metal silanolates, either isolated or formed in situ, offered a significant rate enhancement and broader substrate scope over the use of silanols activated by Brønsted bases such as NaOt-Bu. In addition, the optimized conditions for the cross-coupling of 2-indolylsilanolates were readily applied to the cross-coupling of 2-pyrrolyl-, 2-furyl-, and 2-thienylsilanolates.

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Section: Optimization Of the Cross-coupling Reactionmentioning

confidence: 99%

Section: Optimization Of the Cross-coupling Of N-sem-dimethyl(2-indolmentioning

confidence: 99%

Palladium-Catalyzed Cross-Coupling of Five-Membered Heterocyclic Silanolates

2008

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“…(Trimethylsilyl)ethynyl-and (phenylethynyl)lithium were prepared prior to use by metallation of (trimethylsilyl)acetylene and phenylacetylene, respectively, with nBuLi in dry THF at -78°C and warming to room temperature. [27] According to the general procedure, the reaction of 1 (220 mg, 0.982 mmol) with triphenylindium (0. (Z)-Oct-2-ene (4): [28] According to the general procedure, the reaction of 1 (243 mg, 1.084 mmol) with trimethylindium (0.…”

Section: Methodsmentioning

confidence: 99%

“…(Z)-Undec-5-ene (5): [29] According to the general procedure, the reaction of 1 (238 mg, 1.062 mmol) with tri-n-butylindium (Z)-Nona-1,3-diene (6): [30] According to the general procedure, the reaction of 1 (215 mg, 0.959 mmol) with trivinylindium (0. [(Z)-Non-3-en-1-ynyl]benzene (7): [31] According to the general procedure, the reaction of 1 (240 mg, 1.071 mmol) with tris(phenyl- non-3-en-1-ynyl]silane (8): [32] According to the general procedure, the reaction of 1 (261 mg, [(E)-Hept-1-enyl]benzene (9): [27] According to the general procedure, the reaction of 2 (230 mg, (E)-Oct-2-ene (10): [33] According to the general procedure, the reaction of 2 (224 mg, 1.000 mmol) with trimethylindium (0. (E)-Undec-5-ene (11): [29] According to the general procedure, the reaction of 2 (232 mg, 1.035 mmol) with tri-n-butylindium (E)-Nona-1,3-diene (12): [30] According to the general procedure, the reaction of 2 (210 mg, 0.937 mmol) with trivinylindium (0.…”

Section: Methodsmentioning

confidence: 99%

Palladium‐Catalysed Cross‐Coupling Reactions of Triorganoindium Reagents with Alkenyl Halides

et al. 2008

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The regio-and stereoselectivity of the palladium-catalysed cross-coupling reactions of indium organometallics with stereodefined 1-haloalkenes and 1,1-dihaloalkenes have been studied. Triorganoindium reagents (R 3 In; R = alkyl, alkenyl, aryl and alkynyl) can be stereospecifically coupled with stereodefined alkenyl iodides in good yields and short reaction times under palladium catalysis. Additionally, the palladium-catalysed cross-coupling reaction of R 3 In (90 mol-%) with 1,1-dibromo-1-alkenes gave dicoupling products in high yields. When the reaction was performed with 40 mol-% of aryl-, vinyl-and alkynylindium derivatives, trans-selective monosubstitution products were obtained in moderate to

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“…57 These reactions display superior generality with respect to the acceptor, extremely high stereospecificity for a number of different alkenylsilanolate substitution patterns and overall higher yields than the couplings with the corresponding bromides or iodides (Scheme 10). The absence of byproducts derived from reduction or homocoupling of the electrophile accounts for the better performance of these reactions.…”

Section: Silanolatesmentioning

confidence: 99%

Why You Really Should Consider Using Palladium-Catalyzed Cross-Coupling of Silanols and Silanolates

Denmark

Ambrosi

2015

Org. Process Res. Dev.

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155

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The transition metal-catalyzed cross-coupling of organometallic nucleophiles derived from tin, boron, and zinc with organic electrophiles enjoys a preeminent status among modern synthetic methods for the formation of carbon-carbon bonds. In recent years, organosilanes have emerged as viable alternatives to the conventional reagents, with the added benefits of low cost, low toxicity and high chemical stability. However, silicon-based cross-coupling reactions often require heating in the presence of a fluoride source, which has significantly hampered their widespread acceptance. To address the “fluoride problem”, a new paradigm for palladium-catalyzed, silicon-based cross-coupling reactions has been developed that employs a heretofore underutilized class of silicon reagents, the organosilanols. The use of organosilanols, either in the presence of Brønsted bases or as their silanolate salts, represents an operationally simple and mild alternative to the fluoride-based activation method. Organosilanols are readily available by many well-established methods for introducing carbon-silicon bonds onto alkenes, alkynes, arenes and heteroarenes. Moreover, several different protocols for the generation of alkali metal salts of, vinyl-, alkenyl-, alkynyl-, aryl-, and heteroarylsilanolates have been developed and the advantages of each of these methods have been demonstrated for a number of different coupling classes. This review will describe the development and implementation of cross-coupling reactions of organosilanols and their conjugate bases, silanolates, with a wide variety of substrate classes. In addition, application of these transformations in the total synthesis of complex natural products will also be highlighted. Finally, the unique advantages of organosilicon coupling strategies vis a vis organoboron reagents are discussed.

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Stereospecific Palladium-Catalyzed Cross-Coupling of (E)- and (Z)-Alkenylsilanolates with Aryl Chlorides

Cited by 80 publications

References 20 publications

Palladium-Catalyzed Cross-Coupling of Five-Membered Heterocyclic Silanolates

Palladium-Catalyzed Cross-Coupling of Five-Membered Heterocyclic Silanolates

Palladium‐Catalysed Cross‐Coupling Reactions of Triorganoindium Reagents with Alkenyl Halides

Why You Really Should Consider Using Palladium-Catalyzed Cross-Coupling of Silanols and Silanolates

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