Web Release Date: February 9,
Intramolecular Pd-Catalyzed Carboetherification and Carboamination. Influence of Catalyst Structure on Reaction Mechanism and Product Stereochemistry
Contribution from the Department of Chemistry, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
Received November 2, 2005
Abstract:
The intramolecular Pd-catalyzed carboetherification of alkenes affords 2-indan-1-yltetrahydrofuran products in moderate to good yield with good to excellent levels of diastereoselectivity. The stereochemical outcome of these reactions is dependent on the structure of the Pd catalyst. Use of PCy3 or P[(4-MeO)C6H4]3 as the ligand for Pd leads to syn-addition of the arene and the oxygen atom across the double bond, whereas use of (±)-BINAP or DPP-benzene affords products that result from anti-addition. The catalyst-induced change in stereochemistry is likely due to a change in reaction mechanism. Evidence is presented that suggests the syn-addition products derive from an unprecedented transannular alkene insertion of an 11-membered Pd(Ar)(OR) complex. In contrast, the anti-addition products appear to arise from Wacker-type anti-oxypalladation. Studies on analogous Pd-catalyzed intramolecular carboamination reactions, which afford 2-indan-1-ylpyrrolidines that result from syn-addition, are also described.
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