Hydroaminomethylaton of n-alkenes in a biphasic ionic liquid system

Hydroaminomethylation reactions were performed successfully in an imidazolium-based ionic liq. using a rhodium/sulfoxantphos system by reacting piperidine with different n-alkenes, affording yields higher than 95% of the resulting amine with turnover frequencies of up to 16,000 h-1, along with high regioselectivity for the linear amines with l/b ratios up to 78. Addnl., facile quant. catalyst recovery was accomplished and recycling of the catalyst and product sepn. was achieved by a fast phase sepn. after the reaction. The product distribution was monitored over time at different temps. both in an org. solvent and in the ionic liq. in order to investigate and compare the course of the formation of (side) products and intermediates in these reactions. Furthermore, it was shown that the nature of the rhodium precatalyst has a profound effect on the activity and selectivity. Protic org. solvents and ionic liqs. contg. a C-H acidic bond in the imidazolium part have a beneficial effect on the hydrogenation activity of the catalyst systems.