Roles of Bases in Transition-Metal Catalyzed Organic Reactions

Ouyang, Kunfu; Xi, Zhenfeng

doi:10.6023/a12110984

Cited by 97 publications

(56 citation statements)

References 26 publications

(31 reference statements)

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“…With 1,4‐dioxane as the solvent at 90 °C, the effect of base was first studied (Table 1, entries 1–3). With NaH as the base, the reaction was found to give the desired product 4a in 15 % yield, while KO t Bu and NaHMDS were less effective 17. It was also observed that the amount of base slightly affected the reaction (Table 1, entry 4).…”

Section: Methodsmentioning

confidence: 90%

Mesoporous Carbon Nitride‐Tungsten Oxide Composites for Enhanced Photocatalytic Hydrogen Evolution

et al. 2015

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Composites of mesoporous polymeric carbon nitride and tungsten(VI) oxide show very high photocatalytic activity for the evolution of hydrogen from water under visible light and in the presence of sacrificial electron donors. Already addition of very small amounts of WO3 yields up to a twofold increase in the efficiency when compared to bulk carbon nitrides and their composites and more notably even to the best reported mesoporous carbon nitride-based photocatalytic materials. The higher activity can be attributed to the high surface area and synergetic effect of the carbon nitrides and the WO3 resulting in improved charge separation through a photocatalytic solid-state Z-scheme mechanism.

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Section: Methodsmentioning

confidence: 90%

Mesoporous Carbon Nitride‐Tungsten Oxide Composites for Enhanced Photocatalytic Hydrogen Evolution

et al. 2015

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“…However, only the stronger base ( t BuOK) can eliminate the phosphonium group of PPh 3 , resulting in the shift of the metallafuran ring through the reversible reductive elimination and oxidative addition of the Ar−H bond on the metal center. It is noted that the base has also been found to play an important role in transition‐metal‐catalyzed organic reactions . When D 2 O was used in this phosphonium‐eliminated reaction, the deuterium‐labeled complex 13D was isolated and its structure was supported by 2 D NMR (Figure S33, Supporting Information) and HRMS ( m / z : 1072.2471, Figure S34, Supporting Information) data, which indicated that the proton attached at C2 was originated from water.…”

Section: Resultsmentioning

confidence: 97%

Metallapentalenofuran: Shifting Metallafuran Rings Promoted by Substituent Effects

Hua

Lan

Fei

et al. 2018

Chemistry A European J

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Bulky substituents play important roles in controlling the reaction pathways or producing selected products. This work reports that the shift of metallafuran rings in a metallapentalenofuran complex can be promoted by the substituent effect via a reversible C-H bond reductive elimination and oxidative addition. The starting osmapentalyne, a so-called 7-carbon carbolong complex, was produced by the oxidation of a metallapentalenofuran with FeCl . It was then allowed to react with nucleophiles, followed by a C-H activation, to give the aforementioned metallapentalenofuran complex. This work enriches the family of carbolong complexes and reveals a new strategy to promote, but not prevent reactions by the bulky substituents.

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“…We began our studies by examination of the direct coupling reaction of cinnamyl alcohol 1a with 4-fluorophenylboronic acid in the presence of 5 mol% Ni(cod) 2 , and the results are shown in Table 1. As the bases are often used to facilitate the transmetalation step by forming "ate" complexes with the organoboron reagents, [13] the effects of base were first investigated. While the commonly used t BuOK did not afford the desired coupling product, other inorganic bases such as Cs 2 CO 3 , K 3 PO 4 and K 2 CO 3 improved the reaction efficiency significantly to give the 1-cinnamyl-4-fluorobenzene 2a in 85%-92% yields in the presence of 10 mol% PMe 2 Ph as the ligand at 80 o C in MeCN (Table 1, entries 1-4).…”

Section: Resultsmentioning

confidence: 99%

Nickel‐Catalyzed Direct Coupling of Allylic Alcohols with Organoboron Reagents

2018

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The direct coupling of allylic alcohols with arylboronic acids or their derivatives catalyzed by Ni(cod)2 in the presence of a catalytic amount of base has been developed. A wide variety of allylic substrates or arylboronic acids turned out to be applicable to this catalytic system. The present method does not require the use of ligands for stabilizing the nickel catalyst in most cases or additional activators for activation of allylic alcohols.

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Roles of Bases in Transition-Metal Catalyzed Organic Reactions

Cited by 97 publications

References 26 publications

Mesoporous Carbon Nitride‐Tungsten Oxide Composites for Enhanced Photocatalytic Hydrogen Evolution

Mesoporous Carbon Nitride‐Tungsten Oxide Composites for Enhanced Photocatalytic Hydrogen Evolution

Metallapentalenofuran: Shifting Metallafuran Rings Promoted by Substituent Effects

Nickel‐Catalyzed Direct Coupling of Allylic Alcohols with Organoboron Reagents

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