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A novel selective palladium catalyst system based on bidentate 2,2'-heteroarylarylphosphines and p-TsOH has been developed for hydroformylation reactions (see scheme). By applying optimal conditions good to excellent regioselectivity is obtained for the hydroformylation of aliphatic and aromatic olefins. It is shown that a low acid concentration is crucial for obtaining high degrees of the linear isomer.The palladium-catalyzed hydroformylation of 1-octene has been studied in the presence of different phosphines and acid cocatalysts. The best results are achieved in the presence of in situ-generated palladium complexes with bidentate phosphines. It is demonstrated that the acid concentration is a crucial factor for obtaining high linear selectivity. A novel optimized catalyst based on an arylheteroarylphosphine has been applied for hydroformylation of different aliphatic and aromatic olefins. Good activity and excellent selectivity towards the linear aldehydes is achieved.

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The synthesis of π-acceptor ligands of the type PAr x R 3−x (x = 0−2; R = pyrrolyl, indolyl, carbazolyl; Ar = aryl) (1−8, 10, 12, 13) and P(pyrrolyl) 2 (carbazolyl) (11) is described. These ligands can be prepared in good to excellent yields by treatment of the corresponding free heterocyclic amines with phosphorus chlorides in the presence of base. The utilization of pyrrolyl-, indolyl-, and carbazolylphosphanes in the rhod-