Additive effects on ligand activated allylation of aldehydes by allyltrichlorosilane

Short, J. D.; Attenoux, Sandrine; Berrisford, David J.

doi:10.1016/s0040-4039(97)00312-2

Cited by 57 publications

(30 citation statements)

References 23 publications

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“…Although this is not the case in Lewis base catalyzed reactions involving trifluorosilanes, Berrisford and co-workers have suggested that ionization of the chloride ion from allyltrichlorosilane is possible in the presence of neutral Lewis bases. [299] This ionization implies that the reaction proceeding through a two-phosphoramide pathway involves a six-coordinate, hypervalent cationic siliconium ion. This kind of transition structure still provides nucleophilic activation in the allyl fragment because of the hypervalent nature of the silicon complex.…”

Section: Lewis Base Catalyzed Allylation With Polyhalosilanes: Chiralmentioning

confidence: 99%

Lewis Base Catalysis in Organic Synthesis

2008

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The legacy of Gilbert Newton Lewis (1875-1946) pervades the lexicon of chemical bonding and reactivity. The power of his concept of donor-acceptor bonding is evident in the eponymous foundations of electron-pair acceptors (Lewis acids) and donors (Lewis bases). Lewis recognized that acids are not restricted to those substances that contain hydrogen (Brønsted acids), and helped overthrow the "modern cult of the proton". His discovery ushered in the use of Lewis acids as reagents and catalysts for organic reactions. However, in recent years, the recognition that Lewis bases can also serve in this capacity has grown enormously. Most importantly, it has become increasingly apparent that the behavior of Lewis bases as agents for promoting chemical reactions is not merely as an electronic complement of the cognate Lewis acids: in fact Lewis bases are capable of enhancing both the electrophilic and nucleophilic character of molecules to which they are bound. This diversity of behavior leads to a remarkable versatility for the catalysis of reactions by Lewis bases.

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Section: Lewis Base Catalyzed Allylation With Polyhalosilanes: Chiralmentioning

confidence: 99%

Lewis Base Catalysis in Organic Synthesis

2008

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“…Alternatively, addition of a Lewis base should enhance the reactivity of the nucleophilic silane, which in turn should also lead to allylation. However, Lewis bases, such as DMF [31,32], DMSO [31,33], and HMPA [33,34] are typically inert to AllylSiMe 3 and require AllylSiCl 3 [35], whose silicon atom is more Lewis acidic [30][31][32][33][34][35][36].…”

Section: Organocatalyzed Allylation Of Aldehydes With Allyl Trichloromentioning

confidence: 99%

Asymmetric synthesis: From transition metals to organocatalysis

Kočovský

Malkov

2008

Pure and Applied Chemistry

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Umpolung in the allylation reaction is discussed with examples drawn from transition-metal-catalyzed allylic substitution (with the allylic unit acting as an electrophile) and Lewis base-catalyzed allylation of aldehydes with allyltrichlorosilane (with the allyl acting as a nucleophile). Iridium-catalyzed electrophilic allylation of O-nucleophiles has been employed in our new approach to C-nucleoside analogs, where the C-O bond (rather than C-C) was constructed stereospecifically. Variation of the absolute configuration in the starting segments allowed the synthesis of all four combinations of D/L-α/β-ribosides. In the nucleophilic allylation of aldehydes, chiral pyridine-type N-oxide catalysts are presented, in particular QUINOX and METHOX, and the intriguing behavior of QUINOX is discussed. Here, the π-π interactions between the substrate aldehyde and the catalyst are suggested to rationalize the experimental observations. Good correlation between the calculated energies for the transition states and the experimentally observed enantioselectivities has been obtained.

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“…While allylSiMe 3 is known to react with aldehydes upon activation of the carbonyl group by a Lewis acid, the reaction of allylSiCl 3 requires activation by a Lewis base that coordinates to the silicon (eq 4). 1-3,5,17,39, 40 The latter reaction is believed to proceed through a closed transition state, which controls diastereoselectivity in the case of (E)and (Z)-crotylSiCl 3 , and creates an opportunity for the transfer of chiral information if a chiral Lewis base is employed. Provided the Lewis base dissociates from the silicon with sufficient rate (eq 4), it can act as a catalyst (rather than a stoichiometric reagent).…”

Section: Reactions At Silicon With Heteroatom Nucleophilesmentioning

confidence: 99%

“…However, α,β-unsaturated aldehydes do react readily and give 1,2-addition products. 1, 3,40,50 Stoichiometric Allylation of Aldehydes and Ketones. As discussed above, catalytic allylation is generally confined to highly reactive aldehydes (aromatic, heteroaromatic, and cinnamyltype).…”

Section: Reactions At Silicon With Heteroatom Nucleophilesmentioning

confidence: 99%

Allyltrichlorosilane

Kočovský

2006

Encyclopedia of Reagents for Organic Synthesis

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Additive effects on ligand activated allylation of aldehydes by allyltrichlorosilane

Cited by 57 publications

References 23 publications

Lewis Base Catalysis in Organic Synthesis

Lewis Base Catalysis in Organic Synthesis

Asymmetric synthesis: From transition metals to organocatalysis

Allyltrichlorosilane

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