Transition metal-catalyzed isomerization of N- and O-allylic systems has traditionally been applied to form nucleophilic enamines and enols for reactions with electrophiles. Recent advances in dual transition metal/Br�ndsted acid-catalysis now allow for the generation of synthetically useful iminium and oxocarbenium species through concomitant protonation, thereby providing an efficient entry to these reactive intermediates. The presence of suitably tethered nucleophiles allows for tandem processes that lead to a variety of pharmacologically relevant heterocycles. The overall scope will be illustrated by reactions of cyclic and acyclic electrophilic intermediates, tethered and external p-nucleophiles (aromatics and heteroaromatics), and their applications to natural product total synthesis and diastereo- and enantioselective synthesis.Selected references: E. Ascic, J. F. Jensen, T. E. Nielsen, Angew. Chem. 2011 , 123, 5294�5297; Angew. Chem. Int. Ed. 2011 , 50, 5188�5191; E. Ascic, S. T. Le Quement, M. Ishoey, M. Daugaard, T. E. Nielsen, ACS Comb. Sci. 2012 , 14, 253�257; E. Ascic, C. L. Hansen, S. T. Le Quement, T. E. Nielsen, Chem. Commun. 2012 , 48, 3345�3347; C. L. Hansen, J. W. Clausen, R. G. Ohm, E. Ascic, S. T. Le Quement, D. Tanner, T. E. Nielsen, J. Org. Chem. 2013 , 78, 12545�12565; M. T. Petersen, T. E. Nielsen, Org. Lett. 2013 , 15, 1986�1989; E. Ascic, R. G. Ohm, R. Petersen, M. R. Hansen, C. L. Hansen, D. Madsen, D. Tanner, T. E. Nielsen, Chem. Eur. J. 2014 , 20, 3297-3300.

Synthesis of heterocyclic scaffolds through dual transition metal/Br�nsted acid-catalyzed isomerization/cyclization of allylic ethers and amines

248th National Meeting (2014)

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