Selective synthesis of 5- or 6-aryl octahydrocyclopenta[b]pyrroles from a common precursor through control of competing pathways in a Pd-catalyzed reaction.
The Pd/phosphine-catalyzed reaction of 1 with aryl bromides leads to the selective synthesis of either 6-aryl octahydrocyclopenta[b]pyrroles (3), the corresponding 5-aryl isomers 5, diarylamine 2, or hexahydrocyclopenta[b]pyrrole 4 depending on the structure of the phosphine ligand. These transformations are effective with a variety of different aryl bromides and provide 3-5 with excellent levels of diastereoselectivity (dr > or = 20:1). The changes in product distribution are believed to derive from the influence of Pd-catalyst structure on the relative rates of reductive elimination, beta-hydride elimination, alkene insertion, and alkene displacement processes in a mechanistically complex reaction. The effect of phosphine ligand structure on product distribution is described in detail, along with analysis of a proposed mechanism for these transformations.
Ney
Joshua E
JE
Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan, 48109-1055, USA.
Wolfe
John P
JP
D002384:Catalysis; D003517:Cyclopentanes / Q000138:chemical synthesis*; D008024:Ligands; D009942:Organometallic Compounds / Q000737:chemistry; D010165:Palladium / Q000737:chemistry; D011758:Pyrroles / Q000138:chemical synthesis*; D013329:Structure-Activity Relationship
D003517:Cyclopentanes; D008024:Ligands; D009942:Organometallic Compounds; D011758:Pyrroles; D010165:Palladium