- Ynamide Carbopalladation: A Flexible Route to Mono-, Bi- and Tricyclic Azacycles
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Bromoenynamides represent precursors to a diversity of azacycles by a cascade sequence of carbopalladation followed by cross-coupling/electrocyclization, or reduction processes. Full details of our investigations into intramolecular ynamide carbopalladation are disclosed, which include the first examples of carbopalladation/cross-coupling reactions using potassium organotrifluoroborate salts; and an understanding of factors influencing the success of these processes, including ring size, and the nature of the coupling partner. Additional mechanistic observations are reported, such as the isolation of triene intermediates for electrocyclization. A variety of hetero-Diels-Alder reactions using the product heterocycles are also described, which provide insight into Diels-Alder regioselectivity.
- Campbell, Craig D.,Greenaway, Rebecca L.,Holton, Oliver T.,Walker, P. Ross,Chapman, Helen A.,Russell, C. Adam,Carr, Greg,Thomson, Amber L.,Anderson, Edward A.
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p. 12627 - 12639
(2015/09/01)
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- Reductive cyclization of bromoenynamides with alcohols as hydride source: Synthesis and reactions of 2-amidodienes
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Under basic conditions in alcoholic solvents, bromoenynamides undergo palladium-catalyzed cyclization to cyclic 2-amidodienes in good to excellent yields. This process represents the first use of an alcohol as a hydride source in an alkyne carbopalladation/termination sequence, with the site selectivity of the reduction showing a strong dependence on the tethering ring size (5-8), and the nature of the alcohol and base. Reaction of the dienes with a range of dienophiles (including alkenes, alkynes and arynes) under various conditions gives bi- and tricyclic azacycles, which can be further oxidized to the aromatic azacycles. Copyright
- Greenaway, Rebecca L.,Campbell, Craig D.,Chapman, Helen A.,Anderson, Edward A.
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supporting information
p. 3187 - 3194
(2013/01/15)
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