Nitrogen-Containing Tricyclic and Tetracyclic Compounds by Stereoselective Samarium Diiodide Promoted Cyclizations of Quinolyl-Substituted Ketones – A New Access to Azasteroids
作者:Francesca Aulenta、Ulrike K. Wefelscheid、Irene Brüdgam、Hans-Ulrich Reißig
DOI:10.1002/ejoc.200800019
日期:2008.5
withsamarium diiodidepromotedcyclizations of quinolyl-substitutedketones 6–12 and also the attempted reductive cyclization of carbazole-containing ketone 13. These precursors were prepared by Heck-type coupling reactions of the corresponding hetaryl nonaflates with adequately substituted olefins as a key step. The cyclization of compounds 7–12 led to nitrogen-containing tri- and tetracycliccompounds 23–28
A General Method for Palladium-Catalyzed Reactions of Primary Sulfonamides with Aryl Nonaflates
作者:Shashank Shekhar、Travis B. Dunn、Brian J. Kotecki、Donna K. Montavon、Steven C. Cullen
DOI:10.1021/jo200443u
日期:2011.6.3
A general method for Pd-catalyzed sulfonamidation of aryl nonafluorobutanesulfonates (aryl nonaflates) is described. A biaryl phosphine ligand, t-BuXPhos, formed the most active catalyst, and K3PO4 in tert-amyl alcohol was found to be the optimal base solvent combination for the reaction. The reaction conditions were tolerant of various functional groups such as cyano, nitro, ester, aldehyde, ketone, chloride, carbamate, and phenol. Heterocyclic aryl nonaflates were found to be suitable coupling partners. High yields of the coupled products were obtained from the reactions between inherently disfavored substrates such as electron-rich nonaflates and electron-poor sulfonamides. Kinetic data suggest reductive elimination to be the rate-limiting step for the reaction. The only limitation of this methodology that we have identified is the inability of 2,6-disubstituted aryl nonaflates to efficiently participate in the reaction.
Heck Reactions of Quinoline-Derived Nonaflates
作者:Hans-Ulrich Reissig、Francesca Aulenta
DOI:10.1055/s-2006-948197
日期:2006.11
An efficient synthesis of a series of quinolyl-substituted ketones or ketone precursors via the Heck reaction of 6- or 8-quinolyl nonaflates with an appropriate selection of olefins is presented. These ketones are useful building blocks for the diastereoselective construction of azapolycycles via SmI2-induced intramolecular cyclization of (het)aryl-substituted ketones.