Styrene has been hydroformylated to the linear aldehyde with surprisingly high regioselectivity (l/b up to 22 for styrene) by using Rh complex with tetraphosphorus ligand. To the best of our knowledge, this is the highest linear regioselectivity reported for the hydroformylation of styrene and its derivatives. This protocol is in sharp contrast to other processes that favor producing branched aldehyde (typically >95% branched for most bidentate systems).

A series of new pyrrole-based tetraphosphorus ligands were synthesized and used for Rh-catalyzed isomerization-hydroformylation of internal olefins. It was found that the substituents at the 3,3',5,5'-positions of the biphenyl greatly effected the linear selectivity, and the alkyl-substituted tetraphosphorus ligands gave the best results (for 2-octene, n: i up to 207, for 2-hexene, n: i up to 362).

Alkyl acrylates have been hydroformylated to the linear aldehydes with high regioselectivity (linear/branch > 99/1) and extraordinarily high average turnover frequencies (up to 5400 h À1 ) by using a rhodium complex with a tetraphosphorus ligand. This protocol is in sharp contrast to the most of other processes that favor production of the branched aldehyde (typically > 95% branched for most Rh-catalyzed reaction systems). The high turnover number achieved by this new catalytic system is also remarkable considering the less reactive character of alkyl acrylates to the hydroformylation reaction conditions.

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