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Ziegler-modified Ullmann reaction

The Ziegler-modified Ullmann reaction was used for the total synthesis of pyrrolophenanthridinium alkaloid tortuosine by L.A. Flippin and co-workers. First, A/-Boc-5-methoxyindoline was lithiated at C7 with s-BuLi in the presence of TMEDA, and then it was transmetallated to the corresponding organocopper species that smoothly underwent the Ullmann reaction with a 3-iodoaryl imine. The resulting biaryl product was treated with anhydrous HCI in chloroform, which promoted the cyclization followed by dehydration to give the natural product. [Pg.467]

In general, imines are too reactive to be used to protect carbonyl groups. In a synthesis of juncusol, however, a bromo- and an iodocyclobexylbnine of two identical aromatic aldehydes were coupled by an Ullmann coupling reaction modified by Ziegler. The imines were cleaved by acidic hydrolysis (aq. oxalic acid, THE, 20°, 1 h, 95% yield). Imines of aromatic aldehydes have also been prepared to protect the aldehyde during ring metalation with. -BuLi. ... [Pg.359]


See other pages where Ziegler-modified Ullmann reaction is mentioned: [Pg.271]   
See also in sourсe #XX -- [ Pg.467 ]




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Ziegler-modified Ullmann

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