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Wittig reaction highly trans-selective

A Highly trans-Selective Wittig Reaction BASF Vitamin Ai Synthesis... [Pg.771]

Urns-Epoxides. This unstable ylide (1), when generated as formulated above, reacts with an aliphatic aldehyde at —78° to give a fram-epoxide with almost complete stereoselectivity. The stereochemical selectivity is markedly dependent on the base and also on the counterion of the arsonium salt. Optimum selectivity for the trans-epoxide is obtained with conditions similar to those that induce cis-olefination in Wittig reactions.2 Stereoselection is not so high with aromatic aldehydes. The reagent also reacts with ketones to form trisubstituted epoxides. [Pg.445]

See other pages where Wittig reaction highly trans-selective is mentioned: [Pg.327]    [Pg.447]    [Pg.44]    [Pg.242]    [Pg.1]    [Pg.756]    [Pg.759]    [Pg.756]    [Pg.34]    [Pg.147]    [Pg.664]    [Pg.229]    [Pg.756]    [Pg.442]    [Pg.337]    [Pg.81]    [Pg.244]   
See also in sourсe #XX -- [ Pg.771 ]



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Wittig reaction £-selective

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