JULIA OLEFINATION PDF

TCI uses cookies to personalize and improve your user experience. By continuing on our website, you accept the use of cookies. Reagents: alkylphenyl sulfones, Julia-Kocienski olefination reagents Reactants: aldehydes, ketones Products: E - and Z -olefins Scheme:. My Account.

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TCI uses cookies to personalize and improve your user experience. By continuing on our website, you accept the use of cookies. Reagents: alkylphenyl sulfones, Julia-Kocienski olefination reagents Reactants: aldehydes, ketones Products: E - and Z -olefins Scheme:. My Account. Quick Order Form. Saved Carts. Account Details. Account Sign in. My Account Sign in Register. Account Sign in Register. Contact Us. Maximum quantity allowed is Julia Olefination Reaction The Julia olefination reaction and its various sub-forms is a useful synthetic method to convert aldehydes to olefins using arylsulfones.

Julia olefination has advantages over other olefination techniques in that it offers mild user-friendly conditions over a wide range of substrates. Perhaps the most well-known Julia-Kocienski olefination method, colloquially known as the Modified Julia, uses heteroaromatic sulfone moieties like 1-methyl methylsulfonyl benzimidazole to furnish the transformation. The inclusion of heteroatoms into the aromatic handle modifies the mechanistic pathway resulting in a one-pot procedure and the evolution of SO 2 gas driving the reaction to completion.

Ando, T. Kobayashi, N. Uchida, Org. Julia, J. Paris, Tetrahedron Lett. Review literature The modified Julia olefination: alkene synthesis via the condensation of metallated heteroarylalkylsulfones with carbonyl compounds P.

Blakemore, J. Page Top.

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Julia Olefination

The addition of a phenylsulfonyl carbanion to an aldehyde or ketone leads to an intermediate alcohol, which is esterified in situ. The reductive elimination with sodium amalgam to furnish the alkene takes place in a second step. The Julia-Kociensky Olefination is an alternative procedure, which leads to the olefin in one step. A first possible mechanism proceeds through a planar radical that can rotate freely about the C-C bond. Both diastereomers would thus pass through the same radical intermediate, which can be used to explain the E -selectivity.

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Julia Olefination Reaction

Animation controls: Display controls:. Click the structures and reaction black arrows in sequence to view the 3D models and animations respectively. NOTE: Important charges and non-bonding electrons are shown throughout the animation except during the transition state phase. Initial base promoted elimination of carboxylate leads to a vinyl sulphone which is reductively cleaved to a vinyl radical. The stereoselectivity of the Julia olefination is determined by the radical intermediate.

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Julia olefination

The Modified Julia Olefination enables the preparation of alkenes from benzothiazolyl sulfones and aldehydes in a single step:. Whether the anti or syn intermediate is generated can be influenced to some extent by the choice of reaction conditions:. The intermediates that form react further to give E - and Z -isomers of the alkene:. A mechanistically related nucleophilic addition of the sulfonyl carbanion to a second equivalent of the BT sulfone leads to a side product. The benzothiazolyl group BT can play several roles: in one, it enables a more or less strongly pronounced complexation that influences the selectivity; on the other hand, it can also undergo nucleophilic substitution at the carbon attached to the sulfonyl group, which then becomes a leaving group. Other hetero cyclic substituents can assume these roles, and offer somewhat different selectivity:.

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