Catalyst-free and Solvent-free Cyanosilylation and Knoevenagel Condensation of Aldehydes

Wang, Weifan; Luo, Man; Yao, Weiwei; Ma, Mengtao; Pullarkat, Sumod A.; Xu, Li; Leung, Pak‐Hing

doi:10.1021/acssuschemeng.8b05486

Cited by 65 publications

(36 citation statements)

References 42 publications

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“…Among the many classes of different reactions, in particular addition reactions qualify for designing side‐ and by‐product free transformations without the need of catalysts and solvents at any stage of the preparation. Some selected examples comprise the cycloaddition of aziridines and carbon dioxide, hydrophosphanation of alkenes, Diels‐Alder reactions, Knoevenagel reaction of aldehydes (which is a condensation type reaction), the anomerization of β‐ d ‐glucose pentaacetate or the aza‐Michael reactions . The aza‐Michael reaction involves a nucleophilic amine (the Michael donor) and an electron deficient alkene (the Michael acceptor).…”

Section: Introductionmentioning

confidence: 99%

Solvent‐ and Catalyst‐Free Aza‐Michael Addition of Imidazoles and Related Heterocycles

2020

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This work demonstrates the scope and limitations of the aza‐Michael addition of imidazoles and related heterocycles with electron deficient olefins under solvent‐ and catalyst‐free conditions. The reaction proceeds at 80 °C within hours towards completion as long as the azole derivative is sufficiently soluble in the Michael acceptor, which has been used in small excess. Workup only comprises evaporation of surplus Michael‐acceptor, and no additional solvents are necessary for purifying the products.

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Section: Introductionmentioning

confidence: 99%

Solvent‐ and Catalyst‐Free Aza‐Michael Addition of Imidazoles and Related Heterocycles

2020

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“…As a rare example, cyanosilylation of aldehydes was demonstrated without the use of any catalyst where solvent (DMF) acts as nucleophilic activator . In a recent report, this reaction was achieved even in the absence of solvent but with higher temperature and reaction time whereas under similar conditions ketones showed poor reactivity. Thus, for the cyanosilylation of ketones the use of catalyst is necessary.…”

Section: Figurementioning

confidence: 99%

Three Coordinated Organoaluminum Cation for Rapid and Selective Cyanosilylation of Carbonyls under Solvent‐Free Conditions

et al. 2020

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The well-defined three coordinated electronically unsaturated cationic organoaluminum complex [({(2,6-iPr 2 C 6 H 3 N)P(Ph 2 )} 2 N) AlMe] + [MeB(C 6 F 5 ) 3 ] À (1), has been utilized to catalyze the cyanosilylation of aldehydes and ketones under mild and solvent-free conditions. Moreover, catalyst 1 showed high chemoselective cyanosilylation of aldehydes over ketones, nitriles and olefins. The multinuclear NMR investigations revealed that cyanosilylation proceeds via Lewis adduct formation between 1 and TMSCN thereby activating TMSCN (Si-CN bond) followed by nucleophilic attack of the carbonyl oxygen at the Si center of the activated silane and formation of the product.

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“…This is in agreement with the work of Wang et al who reported low efficiency for the cyanosilylation of ketones in a catalyst‐free environment under elevated reaction temperature. [ 14 ] On the other hand, exposing the reaction mixture containing the nanoplates to 808 nm light ( I = 4.3 W cm −2 ) for 4 min (condition c) produces exceptionally good product yields of 2b–2i with the majority of ketones achieving >90% yields.…”

Section: Figurementioning

confidence: 99%

Ultrathin Near‐Infrared Light Activated Nano‐Hotplate Catalyst

Yeow

2020

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A combined photothermal‐catalytic system that contains a single active element, without using different entities for separate roles (catalytic vs photothermal), is designed here for efficient catalytic reactions. Herein, ultrathin (sub‐6 nm) rectangular‐like KNdF4 nanoplates consisting of 3–4 unit cell layers are prepared where the Nd3+ ions act as a Lewis acid catalyst. In addition, the nanoplates undergo light‐to‐heat conversion when irradiated with NIR light due to cross‐relaxation and nonradiative relaxation processes from excited Nd3+. The cyanosilylation of a series of ketones is performed using the nano‐hotplate catalysts to give near quantitative yields of the cyanohydrin trimethylsilyl ethers. This is because of the high surface area‐to‐volume ratio of the thin nanoplates that provides a large number of surface Nd3+ catalytic sites for reaction. The reaction kinetics are enhanced by the photothermal effect, leading to the observed > 10‐fold increase in product yields.

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Catalyst-free and Solvent-free Cyanosilylation and Knoevenagel Condensation of Aldehydes

Cited by 65 publications

References 42 publications

Solvent‐ and Catalyst‐Free Aza‐Michael Addition of Imidazoles and Related Heterocycles

Solvent‐ and Catalyst‐Free Aza‐Michael Addition of Imidazoles and Related Heterocycles

Three Coordinated Organoaluminum Cation for Rapid and Selective Cyanosilylation of Carbonyls under Solvent‐Free Conditions

Ultrathin Near‐Infrared Light Activated Nano‐Hotplate Catalyst

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